Magnesium(Mg)alloys have shown great prospects as both structural and biomedical materials,while poor corrosion resistance limits their further application.In this work,to avoid the time-consuming and laborious experi...Magnesium(Mg)alloys have shown great prospects as both structural and biomedical materials,while poor corrosion resistance limits their further application.In this work,to avoid the time-consuming and laborious experiment trial,a high-throughput computational strategy based on first-principles calculations is designed for screening corrosion-resistant binary Mg alloy with intermetallics,from both the thermodynamic and kinetic perspectives.The stable binary Mg intermetallics with low equilibrium potential difference with respect to the Mg matrix are firstly identified.Then,the hydrogen adsorption energies on the surfaces of these Mg intermetallics are calculated,and the corrosion exchange current density is further calculated by a hydrogen evolution reaction(HER)kinetic model.Several intermetallics,e.g.Y_(3)Mg,Y_(2)Mg and La_(5)Mg,are identified to be promising intermetallics which might effectively hinder the cathodic HER.Furthermore,machine learning(ML)models are developed to predict Mg intermetallics with proper hydrogen adsorption energy employing work function(W_(f))and weighted first ionization energy(WFIE).The generalization of the ML models is tested on five new binary Mg intermetallics with the average root mean square error(RMSE)of 0.11 eV.This study not only predicts some promising binary Mg intermetallics which may suppress the galvanic corrosion,but also provides a high-throughput screening strategy and ML models for the design of corrosion-resistant alloy,which can be extended to ternary Mg alloys or other alloy systems.展开更多
Mg-6Zn-2X(Fe/Cu/Ni)alloys were prepared through semi-continuous casting,with the aim of identifying a degradable magnesium(Mg)alloy suitable for use in fracturing balls.A comparative analysis was conducted to assess t...Mg-6Zn-2X(Fe/Cu/Ni)alloys were prepared through semi-continuous casting,with the aim of identifying a degradable magnesium(Mg)alloy suitable for use in fracturing balls.A comparative analysis was conducted to assess the impacts of adding Cu and Ni,which result in finer grains and the formation of galvanic corrosion sites.Scanner electronic microscopy examination revealed that precipitated phases concentrated at grain boundaries,forming a semi-continuous network structure that facilitated corrosion penetration in Mg-6Zn-2Cu and Mg-6Zn-2Ni alloys.Pitting corrosion was observed in Mg-6Zn-2Fe,while galvanic corrosion was identified as the primary mechanism in Mg-6Zn-2Cu and Mg-6Zn-2Ni alloys.Among the tests,the Mg-6Zn-2Ni alloy exhibited the highest corrosion rate(approximately 932.9 mm/a)due to its significant potential difference.Mechanical testing showed that Mg-6Zn-2Ni alloy possessed suitable ultimate compressive strength,making it a potential candidate material for degradable fracturing balls,effectively addressing the challenges of balancing strength and degradation rate in fracturing applications.展开更多
Within the past ten years,spark plasma sintering(SPS)has become an increasingly popular process for Mg manufacturing.In the SPS process,interparticle diffusion of compressed particles is rapidly achieved due to the co...Within the past ten years,spark plasma sintering(SPS)has become an increasingly popular process for Mg manufacturing.In the SPS process,interparticle diffusion of compressed particles is rapidly achieved due to the concept of Joule heating.Compared to traditional and additive manufacturing(AM)techniques,SPS gives unique control of the structural and microstructural features of Mg components.By doing so,their mechanical,tribological,and corrosion properties can be tailored.Although great advancements in this field have been made,these pieces of knowledge are scattered and have not been contextualized into a single work.The motivation of this work is to address this scientific gap and to provide a groundwork for understanding the basics of SPS manufacturing for Mg.To do so,the existing body of SPS Mg literature was first surveyed,with a focus on their structural formation and degradation mechanisms.It was found that successful Mg SPS fabrication highly depended on the processing temperature,particle size,and particle crystallinity.The addition of metal and ceramic composites also affected their microstructural features due to the Zener pinning effect.In degradative environments,their performance depends on their structural features and whether they have secondary phased composites.In industrial applications,SPS'd Mg was found to have great potential in biomedical,hydrogen storage,battery,automotive,and recycling sectors.The prospects to advance the field include using Mg as a doping agent for crystallite size refinement and using bulk metallic Mg-based glass powders for amorphous SPS components.Despite these findings,the interactions of multi-composites on the processing-structure-property relationships of SPS Mg is not well understood.In total,this work will provide a useful direction in the SPS field and serve as a milestone for future Mg-based SPS manufacturing.展开更多
Degradable Mg-Zn-Ca alloys with Sr addition were prepared by vacuum melting and hot extrusion.Effect of Sr on microstructure,mechanical and corrosion properties of hot extruded Mg-2Zn-0.5Ca-xSr(x=0,0.5,1.0)alloys was ...Degradable Mg-Zn-Ca alloys with Sr addition were prepared by vacuum melting and hot extrusion.Effect of Sr on microstructure,mechanical and corrosion properties of hot extruded Mg-2Zn-0.5Ca-xSr(x=0,0.5,1.0)alloys was investigated.The results show that Sr addition into Mg-2Zn-0.5Ca alloys produced significant grain refinement in ingots and obvious texture weakening effects in extruded bars.The ultimate compressive strength increased as the Sr content increased,while the ultimate tensile strength increased firstly and then declined with the increasing of Sr content.Electrochemical tests indicated the corrosion current density of the surface parallel to extrusion direction(ED)was much lower than that of the surface perpendicular to ED.In-vitro immersion tests demonstrated the increase in the pH of solution and weight loss of Mg-2Zn-0.5Ca-0.5Sr alloy remain the lowest during immersion tests.The best comprehensive property was obtained in Mg-2Zn-0.5Ca-0.5Sr alloy,which has the largest strength and the best corrosion resistance.展开更多
For the sake of improving the mechanical properties and corrosion resistance of biodegradable Mg alloy synergistically,various content of element V(0,0.05,0.10,0.15,0.20 wt.%)are introduced into an Mg-Zn-Y alloy with ...For the sake of improving the mechanical properties and corrosion resistance of biodegradable Mg alloy synergistically,various content of element V(0,0.05,0.10,0.15,0.20 wt.%)are introduced into an Mg-Zn-Y alloy with long-period stacking ordered(LPSO)structure,and the effects of V on its microstructure,mechanical properties and corrosion resistance are investigated systematically.The results indicate that the grains are effectively refined by V addition,and the primaryα-Mg in Mg-Zn-Y-V0.1 alloy is most significantly refined,with grain size being decreased by 62%.The amount of 18R LPSO structure is increased owing to the V addition.The growth mode of the second phase(W-phase and 18R LPSO structure)is transformed to divorced growth pattern,which ascribes to the thermodynamic drive force of V to promote the nucleation of LPSO phase.Thus,18R LPSO structure presents a continuous distribution.Due to grains refinement and modification of second phase,the tensile strength and strain of alloys are both enhanced effectively.Especially,the ultimate tensile strength and the elongation of V0.1 alloy are 254 MPa and 15.26%,which are 41%and 61%higher than those of V-free alloy,respectively.Owing to the continuously distributed 18R LPSO structure with refined grains and stable product film,the weight loss and hydrogen evolution corrosion rates of V0.1 alloy are 7.1 and 6.2 mmy^(-1),respectively,which are 42.6%and 45.4%lower than those of V-free alloy.展开更多
The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties...The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties,local corrosion properties,and slow strain rate tensile stress corrosion tests.Microstructure characterization techniques such as metallographic microscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM)were also employed.The results indicate that the tensile strength of the alloy produced by T6I6 aging is similar to that produced by T6I4 aging,and it even exceeds 700 MPa.Furthermore,the yield strength increases by 52.7 MPa,reaching 654.8 MPa after T6I6 aging treatment.The maximum depths of intergranular corrosion(IGC)and exfoliation corrosion(EXCO)decrease from 116.3 and 468.5μm to 89.5 and 324.3μm,respectively.The stress corrosion factor also decreases from 2.1%to 1.6%.These findings suggest that the alloy treated with T6I6 aging exhibits both high strength and excellent stress corrosion cracking resistance.Similarly,when the alloy is treated with T6I4,T6I6 and T6I7 aging,the sizes of grain boundary precipitates(GBPs)are found to be 5.2,18.4,and 32.8 nm,respectively.The sizes of matrix precipitates are 4.8,5.7 and 15.7 nm,respectively.The atomic fractions of Zn in GBPs are 9.92 at.%,8.23 at.%and 6.87 at.%,respectively,while the atomic fractions of Mg are 12.66 at.%,8.43 at.%and 7.00 at.%,respectively.Additionally,the atomic fractions of Cu are 1.83 at.%,2.47 at.%and 3.41 at.%,respectively.展开更多
The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investiga...The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investigate its effect on the evolution of the microstructure,magnetic properties and corrosion resistance of NdFeB magnets.Microstructural analysis illustrated that minor In addition generated more grain boundary phases and an abundant amorphous phase at the triple-junction grain boundary.While the addition of In failed to enhance the magnetic isolation effect between adjacent matrix grains,its incorporation fortuitously elevated the electrochemical potential of the In-containing magnets.Besides,during corrosion,an In-rich precipitate phase formed,hindering the ingress of the corrosive medium into the magnet.Consequently,this significantly bolstered the corrosion resistance of the sintered NdFeB magnets.The phase formation,magnetic properties and corrosion resistance of In-doped NdFeB magnets are detailed in this work,which provides new prospects for the preparation of high-performance sintered NdFeB magnets.展开更多
Magnesium(Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair.Rare earth elements(REEs)h...Magnesium(Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair.Rare earth elements(REEs)have demonstrated their effectiveness in tailoring the corrosion and mechanical behavior of Mg alloys.This study methodically investigated the impacts of scandium(Sc)and terbium(Tb)in tailoring the corrosion resistance,mechanical properties,and biocompatibility of Mg–0.5Zn–0.35Zr–0.15Mn(MZZM)alloys fabricated via casting and hot extrusion.Results indicate that addition of Sc and Tb improved the strength of MZZM alloys via grain size reduction and solid solution strengthening mechanisms.The extruded MZZM–(1–2)Sc–(1–2)Tb(wt.%)alloys exhibit compressive strengths within the range of 336–405 MPa,surpassing the minimum required strength of 200 MPa for bone implants by a significant margin.Potentiodynamic polarization tests revealed low corrosion rates of as–cast MZZM(0.25 mm/y),MZZM–2Tb(0.45 mm/y),MZZM–1Sc–1Tb(0.18 mm/y),and MZZM–1Sc–2Tb(0.64 mm/y),and extruded MZZM(0.17 mm/y),MZZM–1Sc(0.15 mm/y),MZZM-2Sc(0.45 mm/y),MZZM-1Tb(0.17 mm/y),MZZM-2Tb(0.10 mm/y),MZZM–1Sc-1Tb(0.14 mm/y),MZZM-1Sc-2Tb(0.40 mm/y),and MZZM–2Sc–2Tb(0.51 mm/y)alloys,which were found lower compared to corrosion rate of high-purity Mg(~1.0 mm/y)reported in the literature.Furthermore,addition of Sc,or Tb,or Sc and Tb to MZZM alloys did not adversely affect the viability of SaOS2 cells,but enhanced their initial cell attachment,proliferation,and spreading shown via polygonal shapes and filipodia.This study emphasizes the benefits of incorporating Sc and Tb elements in MZZM alloys,as they effectively enhance corrosion resistance,mechanical properties,and biocompatibility simultaneously.展开更多
The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,inte...The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.展开更多
A novel double side friction stir Z shape lap-butt welding(DS-FSZW)process was proposed to achieve excellent mechanical properties of Al/Cu medium-thick dissimilar joints.The influence of welding parameters on weld mi...A novel double side friction stir Z shape lap-butt welding(DS-FSZW)process was proposed to achieve excellent mechanical properties of Al/Cu medium-thick dissimilar joints.The influence of welding parameters on weld microstructure and properties of DS-FSZW joint were systematically investigated.It indicated that defect-free medium-thick Al/Cu DS-FSZW joint could be achieved under an optimal welding parameter.DS-FSZW joint was prone to form void defects in the bottom of the second-pass weld.The recrystallization mechanisms at the top and middle of the weld nugget zone(WNZ)were continuous dynamic recrystallization(CDRX)and geometric dynamic recrystallization(GDRX).While the major recrystallization mechanism at the bottom of the WNZ was GDRX.DS-FSZW joint of the optimal welding condition with 850 r/min-400 mm/min was produced with a continuous thin and crack-free IMCs layer at the Al/Cu interface,and the maximum tensile strength of this joint is 160.57 MPa,which is equivalent to 65.54%of pure Cu base material.Moreover,the corrosion resistance of Al/Cu DS-FSZW joints also achieved its maximum value at the optimal welding parameter of 850 r/min-400 mm/min.It demonstrates that the DS-FSZW process can simultaneously produce medium-thick Al/Cu joints with excellent mechanical performance and corrosion resistance.展开更多
This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-pri...This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-principles calculations based on Density Functional Theory(DFT)and the quasi-harmonic approximation(QHA),the combined properties of the Mg-Li-Al phase are explored,revealing superior incompressibility,shear resistance,and stiffness compared to individual elements.The review highlights the brittleness of the alloy,supported by B/G ratios,Cauchy pressures,and Poisson’s ratios.Electronic structure analysis shows metallic behavior with varied covalent bonding characteristics,while Mulliken population analysis emphasizes significant electron transfer within the alloy.This paper also studied thermodynamic properties,including Debye temperature,heat capacity,enthalpy,free energy,and entropy,which are precisely examined,highlighting the Mg-Li-Al phase sensitive to thermal conductivity and thermal performance potential.Phonon density of states(PHDOS)confirms dynamic stability,while anisotropic sound velocities reveal elastic anisotropies.This comprehensive review not only consolidates the current understanding of the Mg-Li-Al alloy’s properties but also proposes innovative strategies for enhancing corrosion resistance.Among these strategies is the introduction of a corrosion barrier akin to the Mg-Li-Al network,which holds promise for advancing both the applications and performance of these alloys.This review serves as a crucial foundation for future research aimed at optimizing alloy design and processing methods.展开更多
In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of diff...In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of different concentrations of Ho on the microstructural characteristics,tensile and compressive properties,corrosion resistance,and biocompatibility were investigated.The microstructures of the extruded Mg-1Zr-0.5Sr-xHo(x=0.5,1.5,and 4 wt.%)alloys consisted ofα-Mg matrix,fineα-Zr particles,and intermetallic phase particles of Mg_(17)Sr_(2) and Ho_(2)Mg mainly distributed at the grain boundaries.Extensive{1012}tensile twins were observed in the partially recrystallized samples of Mg-1Zr-0.5Sr-0.5Ho and Mg-1Zr-0.5Sr-1.5Ho.Further addition of Ho to 4 wt.%resulted in a complete recrystallization due to activation of the particle stimulated nucleation around the Mg_(17)Sr_(2) particles.The evolution of a rare earth(RE)texture was observed with the Ho addition,which resulted in the weakened basal and prismatic textures.Furthermore,a drastic increase of 200%in tensile elongation and 89%in compressive strain was observed with Ho addition increased from 0.5 to 4 wt%,respectively.The tension-compression yield asymmetry was significantly decreased from 0.62 for Mg-1Zr-0.5Sr-0.5Ho to 0.98 for Mg-1Zr-0.5Sr-4Ho due to the weakening of textures.Corrosion analysis of the extruded Mg-Zr-Sr-Ho alloys revealed the presence of pitting corrosion.A minimum corrosion rate of 4.98 mm y^(−1) was observed in Mg-1Zr-0.5Sr-0.5Ho alloy.The enhanced corrosion resistance is observed due to the presence of Ho_(2)O_(3) in the surface film which reduced galvanic effect.The formation of a stabilized surface film due to the Ho_(2)O_(3) was confirmed through the electrical impedance spectroscopy and XPS analysis.An in vitro cytotoxicity assessment revealed good biocompatibility and cell adhesion in relation to SaOS2 cells.展开更多
FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segrega...FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and pre-pare uniform HEA coatings.Scanning electron microscopy,transmission electron microscopy,and X-ray diffractometry were employed to characterize these coatings’microstructure and phase composition.The hardness,elastic modulus,and fracture toughness of coatings were tested,and the corrosion resistance was analyzed in simulated seawater.Results show that the hardness of the coating is HV0.1606.15,the modulus of elasticity is 128.42 GPa,and the fracture toughness is 43.98 MPa·m^(1/2).The corrosion potential of the coating in 3.5wt%NaCl solution is-0.49 V,and the corrosion current density is 1.2×10^(−6)A/cm^(2).The electrochemical system comprises three parts:the electrolyte,the adsorption and metallic oxide films produced during immersion,and the FeCoNiCrMo HEA coating.Over in-creasingly long periods,the corrosion reaction rate increases first and then decreases,the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution,and the internal reaction of the coating declines.展开更多
To enhance the microbiologically influenced corrosion(MIC)resistance of FeCoNiCrMn high entropy alloy(HEAs),a series of Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs were prepared.Microstructural characteristics...To enhance the microbiologically influenced corrosion(MIC)resistance of FeCoNiCrMn high entropy alloy(HEAs),a series of Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs were prepared.Microstructural characteristics,corrosion behavior(morphology observation and electrochemical properties),and antimicrobial performance of Fe_(x)Cu_((1−x))CoNiCrMn HEAs were evaluated in a medium inoculated with typical corrosive microorganism Pseudomonas aeruginosa.The aim was to identify copper-containing FeCoNiCrMn HEAs that balance corrosion resistance and antimicrobial properties.Results revealed that all Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs exhibited an FCC(face centered cubic)phase,with significant grain refinement observed in Fe_(0.75)Cu_(0.25)CoNiCrMn HEA.Electrochemical tests indicated that Fe_(0.75)Cu_(0.25)CoNiCrMn HEA demonstrated lower corrosion current density(i_(corr))and pitting potential(E_(pit))compared to other Fe_(x)Cu_((1−x))CoNiCrMn HEAs in P.aeruginosa-inoculated medium,exhibiting superior resistance to MIC.Anti-microbial tests showed that after 14 d of immersion,Fe_(0.75)Cu_(0.25)CoNiCrMn achieved an antibacterial rate of 89.5%,effectively inhibiting the adhesion and biofilm formation of P.aeruginosa,thereby achieving resistance to MIC.展开更多
Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosi...Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosion treated samples were then subjected to high-temperature experiments at 25,300,600,and 900℃,and triaxial compression experiments were conducted in the laboratory.The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality,wave velocity,porosity and compression failure characteristics of the rock.Based on the Lemaitre strain equivalent hypothesis theory,the damage degree of rock material was described by introducing damage variables,and the spatial mobilized plane(SMP)criterion was adopted.The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process,which verified the rationality and reliability of the model parameters.The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage,which had certain practical significance for rock engineering construction.展开更多
The in-situ growing approach was utilized in this article to construct the magnesium–aluminum layered double hydroxide(MgAl-LDH)film on the surface of a 1060 aluminum anodized film.To improve the corrosion resistance...The in-situ growing approach was utilized in this article to construct the magnesium–aluminum layered double hydroxide(MgAl-LDH)film on the surface of a 1060 aluminum anodized film.To improve the corrosion resistance and friction qualities of aluminum alloy,the MgAl-LDH coating was treated using stearic acid(SA)and thiourea(TU).The aluminum substrate and anodized aluminum film layer corroded to varying degrees after 24 h of immersion in 3.5%(mass)NaCl solution,while the modified hydrotalcite film layer continued to exhibit the same microscopic morphology even after being immersed for 7 d.The results show that the synergistic action of thiourea and stearic acid can effectively improve the corrosion resistance of the MgAl-LDH substrate.The tribological testing reveals that the hydrotalcite film layer and the modified film layer lowered the friction coefficient of the anodized aluminum surface substantially.The results of the simulations and experiments demonstrate that SA forms the dense LDH-TU interlayer film layer by exchanging NO_(3)^(-)ions between TU layers on the one hand and the LDH-SA film layer by adsorption on the surface of LDH on the other.Together,these two processes create LDH-TUSA,which can significantly increase the substrate’s corrosion resistance.This synergistically modified superhydrophobic and retardant hydrotalcite film layer offers a novel approach to the investigation of wear reduction and corrosion protection on the surface of aluminum and its alloys.展开更多
In this study,extrusion was performed on Mg-Zr-Sr-Dy alloys for improving their mechanical,corrosion,and biocompatibility properties.Effects of extrusion and alloying elements on the microstructural characteristics,te...In this study,extrusion was performed on Mg-Zr-Sr-Dy alloys for improving their mechanical,corrosion,and biocompatibility properties.Effects of extrusion and alloying elements on the microstructural characteristics,tensile and compressive strengths,corrosion behavior,and biocompatibility were investigated.The Mg-Zr-Sr-Dy alloys were composed of an α-Mg matrix containing {10■2} extension twins and secondary phases of intermetallic compounds Mg_(17)Sr_(2) and Mg_(2)Dy.Evolution of basal and rare earth(RE) textures was observed in the extruded alloys and an increase in Dy content to 2 wt.% resulted in texture randomization and strengthening of the RE component,mainly due to particle-stimulated nucleation and a change from discontinuous dynamic recrystallization to continuous dynamic recrystallization,which also led to an improved tension-compression yield asymmetry of 0.87.Extrusion of the alloys significantly enhanced their tensile and compressive properties due to improved distribution of alloying elements and formation of textures.Corrosion rates tested by hydrogen evolution testing,potentiodynamic polarization,and electrical impedance spectroscopy showed similar trends for each composition,and the lowest corrosion rate of 3.37 mmy^(-1) was observed for the Mg-1Zr-0.5Sr-1Dy in the potentiodynamic polarization testing.Dy_(2)O_(3) was observed in the inner layers of the Mg(OH)_(2) protective films,whose protective efficacy was confirmed by charge-transfer and film resistances.A comparison among the minimum CRs observed in this study and previously studied as-cast Mg-Zr-Sr-Dy and extruded Mg-Zr-Sr alloys,demonstrates that both the extrusion process and addition of Dy in Mg-Zr-Sr improved the CR.Similarly,extruded Mg-Zr-Sr-Dy alloys showed improved cell viability and adhesion of human osteoblast-like SaOS2 cells due to increased corrosion resistance and enhanced Sr distribution within the Mg matrix.展开更多
To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnes...To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.展开更多
Mg69Zn27Ca4 alloys with diameters of 1.5, 2 and 3 mm were fabricated using copper mold injection casting method. Microstructural analysis reveals that the alloy with a diameter of 1.5 mm is almost completely composed ...Mg69Zn27Ca4 alloys with diameters of 1.5, 2 and 3 mm were fabricated using copper mold injection casting method. Microstructural analysis reveals that the alloy with a diameter of 1.5 mm is almost completely composed of amorphous phase. However, with the cooling rate decline, a little α-Mg and MgZn dendrites can be found in the amorphous matrix. Based on the microstructural and tensile results, the ductile dendrites are conceived to be highly responsible for the enhanced compressive strain from 1.3% to 3.1% by increasing the sample diameter from 1.5 mm to 3 mm. In addition, the Mg69Zn27Ca4 alloy with 1.5 mm diameter has the best corrosion properties. The current Mg-based alloys show much better corrosion resistance than the traditionally commercial wrought magnesium alloy ZK60 in simulated sea-water.展开更多
Long period stacking ordered（LPSO） structure phases were prepared by conventional solidification method in Mg（94）Zn3YxGd（3-x）（x=3,2,1.5,1,mole fraction） alloys,the microstructures,corrosion and compressive mec...Long period stacking ordered（LPSO） structure phases were prepared by conventional solidification method in Mg（94）Zn3YxGd（3-x）（x=3,2,1.5,1,mole fraction） alloys,the microstructures,corrosion and compressive mechanical properties of which were investigated,separately.The results reveal that the microstructures of the as-cast Mg（94）Zn3YxGd（3-x） alloys,with n（Zn）/n（Y＋Gd）=1：1,consist of α（Mg） phase,Mg3Zn3RE2（W） phase,Mg（12）ZnRE（14H-LPSO） phase and a few bright cube-shaped Mg-Y-Gd phases.The formation and the distribution of LPSO-phase in the alloys can be influenced by the content of Gd.The volume fraction of 14H-LPSO phase increases first and then decreases with the increase of the Gd content.For the electrochemical impedance spectroscopy（EIS） measurement,a R（Q（R（QR））） model was used to fit the test results in 3.5%（mass fraction） NaCl solution at room temperature.The corrosion current densities of all samples are about 10-（-5） A/cm-2.When x（Gd）≤1%,Mg-Zn-Y-（Gd）alloy shows good corrosion resistance,which is better than that of the commercial AZ91 D magnesium alloy.The corrosion rate increases when the Gd content is higher than 1.5%.At room temperature,the compressive properties of Mg-Zn-Y-（Gd） alloys increase remarkably with the increase of the volume fraction of LPSO phase.In addition,the pinning effect of W-phase and dispersive cube-shaped Mg-Y-Gd phase is beneficial to improving the mechanical properties of as-cast Mg（94）Zn3YxGd（3-x） alloy in deformation process.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0701202,No.2017YFB0701500 and No.2020YFB1505901)National Natural Science Foundation of China(General Program No.51474149,52072240)+3 种基金Shanghai Science and Technology Committee(No.18511109300)Science and Technology Commission of the CMC(2019JCJQZD27300)financial support from the University of Michigan and Shanghai Jiao Tong University joint funding,China(AE604401)Science and Technology Commission of Shanghai Municipality(No.18511109302).
文摘Magnesium(Mg)alloys have shown great prospects as both structural and biomedical materials,while poor corrosion resistance limits their further application.In this work,to avoid the time-consuming and laborious experiment trial,a high-throughput computational strategy based on first-principles calculations is designed for screening corrosion-resistant binary Mg alloy with intermetallics,from both the thermodynamic and kinetic perspectives.The stable binary Mg intermetallics with low equilibrium potential difference with respect to the Mg matrix are firstly identified.Then,the hydrogen adsorption energies on the surfaces of these Mg intermetallics are calculated,and the corrosion exchange current density is further calculated by a hydrogen evolution reaction(HER)kinetic model.Several intermetallics,e.g.Y_(3)Mg,Y_(2)Mg and La_(5)Mg,are identified to be promising intermetallics which might effectively hinder the cathodic HER.Furthermore,machine learning(ML)models are developed to predict Mg intermetallics with proper hydrogen adsorption energy employing work function(W_(f))and weighted first ionization energy(WFIE).The generalization of the ML models is tested on five new binary Mg intermetallics with the average root mean square error(RMSE)of 0.11 eV.This study not only predicts some promising binary Mg intermetallics which may suppress the galvanic corrosion,but also provides a high-throughput screening strategy and ML models for the design of corrosion-resistant alloy,which can be extended to ternary Mg alloys or other alloy systems.
基金financially supported by the Key Scientific Research Project in Shanxi Province,China(No.202102050201003)the National Natural Science Foundation of China(No.52071227)+2 种基金the Natural Science Foundation of Shanxi Province,China(No.202103021223293)the Central Guiding Science and Technology Development of Local Fund,China(No.YDZJSK20231A046)the Postgraduate Education Innovation Project of Shanxi Province,China(No.2023Y686)。
文摘Mg-6Zn-2X(Fe/Cu/Ni)alloys were prepared through semi-continuous casting,with the aim of identifying a degradable magnesium(Mg)alloy suitable for use in fracturing balls.A comparative analysis was conducted to assess the impacts of adding Cu and Ni,which result in finer grains and the formation of galvanic corrosion sites.Scanner electronic microscopy examination revealed that precipitated phases concentrated at grain boundaries,forming a semi-continuous network structure that facilitated corrosion penetration in Mg-6Zn-2Cu and Mg-6Zn-2Ni alloys.Pitting corrosion was observed in Mg-6Zn-2Fe,while galvanic corrosion was identified as the primary mechanism in Mg-6Zn-2Cu and Mg-6Zn-2Ni alloys.Among the tests,the Mg-6Zn-2Ni alloy exhibited the highest corrosion rate(approximately 932.9 mm/a)due to its significant potential difference.Mechanical testing showed that Mg-6Zn-2Ni alloy possessed suitable ultimate compressive strength,making it a potential candidate material for degradable fracturing balls,effectively addressing the challenges of balancing strength and degradation rate in fracturing applications.
文摘Within the past ten years,spark plasma sintering(SPS)has become an increasingly popular process for Mg manufacturing.In the SPS process,interparticle diffusion of compressed particles is rapidly achieved due to the concept of Joule heating.Compared to traditional and additive manufacturing(AM)techniques,SPS gives unique control of the structural and microstructural features of Mg components.By doing so,their mechanical,tribological,and corrosion properties can be tailored.Although great advancements in this field have been made,these pieces of knowledge are scattered and have not been contextualized into a single work.The motivation of this work is to address this scientific gap and to provide a groundwork for understanding the basics of SPS manufacturing for Mg.To do so,the existing body of SPS Mg literature was first surveyed,with a focus on their structural formation and degradation mechanisms.It was found that successful Mg SPS fabrication highly depended on the processing temperature,particle size,and particle crystallinity.The addition of metal and ceramic composites also affected their microstructural features due to the Zener pinning effect.In degradative environments,their performance depends on their structural features and whether they have secondary phased composites.In industrial applications,SPS'd Mg was found to have great potential in biomedical,hydrogen storage,battery,automotive,and recycling sectors.The prospects to advance the field include using Mg as a doping agent for crystallite size refinement and using bulk metallic Mg-based glass powders for amorphous SPS components.Despite these findings,the interactions of multi-composites on the processing-structure-property relationships of SPS Mg is not well understood.In total,this work will provide a useful direction in the SPS field and serve as a milestone for future Mg-based SPS manufacturing.
基金supports from the key research and development program of Shandong Province(Grant No.2021ZLGX01).
文摘Degradable Mg-Zn-Ca alloys with Sr addition were prepared by vacuum melting and hot extrusion.Effect of Sr on microstructure,mechanical and corrosion properties of hot extruded Mg-2Zn-0.5Ca-xSr(x=0,0.5,1.0)alloys was investigated.The results show that Sr addition into Mg-2Zn-0.5Ca alloys produced significant grain refinement in ingots and obvious texture weakening effects in extruded bars.The ultimate compressive strength increased as the Sr content increased,while the ultimate tensile strength increased firstly and then declined with the increasing of Sr content.Electrochemical tests indicated the corrosion current density of the surface parallel to extrusion direction(ED)was much lower than that of the surface perpendicular to ED.In-vitro immersion tests demonstrated the increase in the pH of solution and weight loss of Mg-2Zn-0.5Ca-0.5Sr alloy remain the lowest during immersion tests.The best comprehensive property was obtained in Mg-2Zn-0.5Ca-0.5Sr alloy,which has the largest strength and the best corrosion resistance.
基金supported financially by the National Natural Science Foundation of China(Nos.51825401,51474153 and 51574175)。
文摘For the sake of improving the mechanical properties and corrosion resistance of biodegradable Mg alloy synergistically,various content of element V(0,0.05,0.10,0.15,0.20 wt.%)are introduced into an Mg-Zn-Y alloy with long-period stacking ordered(LPSO)structure,and the effects of V on its microstructure,mechanical properties and corrosion resistance are investigated systematically.The results indicate that the grains are effectively refined by V addition,and the primaryα-Mg in Mg-Zn-Y-V0.1 alloy is most significantly refined,with grain size being decreased by 62%.The amount of 18R LPSO structure is increased owing to the V addition.The growth mode of the second phase(W-phase and 18R LPSO structure)is transformed to divorced growth pattern,which ascribes to the thermodynamic drive force of V to promote the nucleation of LPSO phase.Thus,18R LPSO structure presents a continuous distribution.Due to grains refinement and modification of second phase,the tensile strength and strain of alloys are both enhanced effectively.Especially,the ultimate tensile strength and the elongation of V0.1 alloy are 254 MPa and 15.26%,which are 41%and 61%higher than those of V-free alloy,respectively.Owing to the continuously distributed 18R LPSO structure with refined grains and stable product film,the weight loss and hydrogen evolution corrosion rates of V0.1 alloy are 7.1 and 6.2 mmy^(-1),respectively,which are 42.6%and 45.4%lower than those of V-free alloy.
基金the Tianjin Key Laboratory of Fastening and Connection Technology Enterprises 2022—2023,China(No.TKLF2022-02-C-02)the technical support from the School of Materials Science and Engineering,Central South University,China.
文摘The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties,local corrosion properties,and slow strain rate tensile stress corrosion tests.Microstructure characterization techniques such as metallographic microscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM)were also employed.The results indicate that the tensile strength of the alloy produced by T6I6 aging is similar to that produced by T6I4 aging,and it even exceeds 700 MPa.Furthermore,the yield strength increases by 52.7 MPa,reaching 654.8 MPa after T6I6 aging treatment.The maximum depths of intergranular corrosion(IGC)and exfoliation corrosion(EXCO)decrease from 116.3 and 468.5μm to 89.5 and 324.3μm,respectively.The stress corrosion factor also decreases from 2.1%to 1.6%.These findings suggest that the alloy treated with T6I6 aging exhibits both high strength and excellent stress corrosion cracking resistance.Similarly,when the alloy is treated with T6I4,T6I6 and T6I7 aging,the sizes of grain boundary precipitates(GBPs)are found to be 5.2,18.4,and 32.8 nm,respectively.The sizes of matrix precipitates are 4.8,5.7 and 15.7 nm,respectively.The atomic fractions of Zn in GBPs are 9.92 at.%,8.23 at.%and 6.87 at.%,respectively,while the atomic fractions of Mg are 12.66 at.%,8.43 at.%and 7.00 at.%,respectively.Additionally,the atomic fractions of Cu are 1.83 at.%,2.47 at.%and 3.41 at.%,respectively.
基金funded by Ningbo Key R&D Plan and“Unveiling and Leading”(Grant No.2023Z093)Ningbo Science and Technology Innovation 2025 Major Special Project(Grant No.2022Z106)Hezhou City Central Leading Local Science and Technology Development Special Fund Project(Grant No.HK ZY2022002).
文摘The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investigate its effect on the evolution of the microstructure,magnetic properties and corrosion resistance of NdFeB magnets.Microstructural analysis illustrated that minor In addition generated more grain boundary phases and an abundant amorphous phase at the triple-junction grain boundary.While the addition of In failed to enhance the magnetic isolation effect between adjacent matrix grains,its incorporation fortuitously elevated the electrochemical potential of the In-containing magnets.Besides,during corrosion,an In-rich precipitate phase formed,hindering the ingress of the corrosive medium into the magnet.Consequently,this significantly bolstered the corrosion resistance of the sintered NdFeB magnets.The phase formation,magnetic properties and corrosion resistance of In-doped NdFeB magnets are detailed in this work,which provides new prospects for the preparation of high-performance sintered NdFeB magnets.
基金the financial support provided by the Australian Research Council(ARC)through the Future Fellowship(FT160100252)the Discovery Project(DP170102557)for this research。
文摘Magnesium(Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair.Rare earth elements(REEs)have demonstrated their effectiveness in tailoring the corrosion and mechanical behavior of Mg alloys.This study methodically investigated the impacts of scandium(Sc)and terbium(Tb)in tailoring the corrosion resistance,mechanical properties,and biocompatibility of Mg–0.5Zn–0.35Zr–0.15Mn(MZZM)alloys fabricated via casting and hot extrusion.Results indicate that addition of Sc and Tb improved the strength of MZZM alloys via grain size reduction and solid solution strengthening mechanisms.The extruded MZZM–(1–2)Sc–(1–2)Tb(wt.%)alloys exhibit compressive strengths within the range of 336–405 MPa,surpassing the minimum required strength of 200 MPa for bone implants by a significant margin.Potentiodynamic polarization tests revealed low corrosion rates of as–cast MZZM(0.25 mm/y),MZZM–2Tb(0.45 mm/y),MZZM–1Sc–1Tb(0.18 mm/y),and MZZM–1Sc–2Tb(0.64 mm/y),and extruded MZZM(0.17 mm/y),MZZM–1Sc(0.15 mm/y),MZZM-2Sc(0.45 mm/y),MZZM-1Tb(0.17 mm/y),MZZM-2Tb(0.10 mm/y),MZZM–1Sc-1Tb(0.14 mm/y),MZZM-1Sc-2Tb(0.40 mm/y),and MZZM–2Sc–2Tb(0.51 mm/y)alloys,which were found lower compared to corrosion rate of high-purity Mg(~1.0 mm/y)reported in the literature.Furthermore,addition of Sc,or Tb,or Sc and Tb to MZZM alloys did not adversely affect the viability of SaOS2 cells,but enhanced their initial cell attachment,proliferation,and spreading shown via polygonal shapes and filipodia.This study emphasizes the benefits of incorporating Sc and Tb elements in MZZM alloys,as they effectively enhance corrosion resistance,mechanical properties,and biocompatibility simultaneously.
基金Project(202302AB080024)supported by the Department of Science and Technology of Yunnan Province,China。
文摘The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.
基金Supported by National Natural Science Foundation of China(Grant Nos.52275349,52035005)Key Research and Development Program of Shandong Province of China(Grant No.2021ZLGX01)Qilu Young Scholar Program of Shandong University of China.
文摘A novel double side friction stir Z shape lap-butt welding(DS-FSZW)process was proposed to achieve excellent mechanical properties of Al/Cu medium-thick dissimilar joints.The influence of welding parameters on weld microstructure and properties of DS-FSZW joint were systematically investigated.It indicated that defect-free medium-thick Al/Cu DS-FSZW joint could be achieved under an optimal welding parameter.DS-FSZW joint was prone to form void defects in the bottom of the second-pass weld.The recrystallization mechanisms at the top and middle of the weld nugget zone(WNZ)were continuous dynamic recrystallization(CDRX)and geometric dynamic recrystallization(GDRX).While the major recrystallization mechanism at the bottom of the WNZ was GDRX.DS-FSZW joint of the optimal welding condition with 850 r/min-400 mm/min was produced with a continuous thin and crack-free IMCs layer at the Al/Cu interface,and the maximum tensile strength of this joint is 160.57 MPa,which is equivalent to 65.54%of pure Cu base material.Moreover,the corrosion resistance of Al/Cu DS-FSZW joints also achieved its maximum value at the optimal welding parameter of 850 r/min-400 mm/min.It demonstrates that the DS-FSZW process can simultaneously produce medium-thick Al/Cu joints with excellent mechanical performance and corrosion resistance.
文摘This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-principles calculations based on Density Functional Theory(DFT)and the quasi-harmonic approximation(QHA),the combined properties of the Mg-Li-Al phase are explored,revealing superior incompressibility,shear resistance,and stiffness compared to individual elements.The review highlights the brittleness of the alloy,supported by B/G ratios,Cauchy pressures,and Poisson’s ratios.Electronic structure analysis shows metallic behavior with varied covalent bonding characteristics,while Mulliken population analysis emphasizes significant electron transfer within the alloy.This paper also studied thermodynamic properties,including Debye temperature,heat capacity,enthalpy,free energy,and entropy,which are precisely examined,highlighting the Mg-Li-Al phase sensitive to thermal conductivity and thermal performance potential.Phonon density of states(PHDOS)confirms dynamic stability,while anisotropic sound velocities reveal elastic anisotropies.This comprehensive review not only consolidates the current understanding of the Mg-Li-Al alloy’s properties but also proposes innovative strategies for enhancing corrosion resistance.Among these strategies is the introduction of a corrosion barrier akin to the Mg-Li-Al network,which holds promise for advancing both the applications and performance of these alloys.This review serves as a crucial foundation for future research aimed at optimizing alloy design and processing methods.
基金the financial support for this research by the Australian Research Council(ARC)through the Future Fellowship(FT160100252)the Discovery Project(DP170102557)。
文摘In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of different concentrations of Ho on the microstructural characteristics,tensile and compressive properties,corrosion resistance,and biocompatibility were investigated.The microstructures of the extruded Mg-1Zr-0.5Sr-xHo(x=0.5,1.5,and 4 wt.%)alloys consisted ofα-Mg matrix,fineα-Zr particles,and intermetallic phase particles of Mg_(17)Sr_(2) and Ho_(2)Mg mainly distributed at the grain boundaries.Extensive{1012}tensile twins were observed in the partially recrystallized samples of Mg-1Zr-0.5Sr-0.5Ho and Mg-1Zr-0.5Sr-1.5Ho.Further addition of Ho to 4 wt.%resulted in a complete recrystallization due to activation of the particle stimulated nucleation around the Mg_(17)Sr_(2) particles.The evolution of a rare earth(RE)texture was observed with the Ho addition,which resulted in the weakened basal and prismatic textures.Furthermore,a drastic increase of 200%in tensile elongation and 89%in compressive strain was observed with Ho addition increased from 0.5 to 4 wt%,respectively.The tension-compression yield asymmetry was significantly decreased from 0.62 for Mg-1Zr-0.5Sr-0.5Ho to 0.98 for Mg-1Zr-0.5Sr-4Ho due to the weakening of textures.Corrosion analysis of the extruded Mg-Zr-Sr-Ho alloys revealed the presence of pitting corrosion.A minimum corrosion rate of 4.98 mm y^(−1) was observed in Mg-1Zr-0.5Sr-0.5Ho alloy.The enhanced corrosion resistance is observed due to the presence of Ho_(2)O_(3) in the surface film which reduced galvanic effect.The formation of a stabilized surface film due to the Ho_(2)O_(3) was confirmed through the electrical impedance spectroscopy and XPS analysis.An in vitro cytotoxicity assessment revealed good biocompatibility and cell adhesion in relation to SaOS2 cells.
基金supported by the National Natural Natural Science Foundation of China(No.52271055)the Natural Science Foundation of Hebei Province,China(No.E2024202154).
文摘FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and pre-pare uniform HEA coatings.Scanning electron microscopy,transmission electron microscopy,and X-ray diffractometry were employed to characterize these coatings’microstructure and phase composition.The hardness,elastic modulus,and fracture toughness of coatings were tested,and the corrosion resistance was analyzed in simulated seawater.Results show that the hardness of the coating is HV0.1606.15,the modulus of elasticity is 128.42 GPa,and the fracture toughness is 43.98 MPa·m^(1/2).The corrosion potential of the coating in 3.5wt%NaCl solution is-0.49 V,and the corrosion current density is 1.2×10^(−6)A/cm^(2).The electrochemical system comprises three parts:the electrolyte,the adsorption and metallic oxide films produced during immersion,and the FeCoNiCrMo HEA coating.Over in-creasingly long periods,the corrosion reaction rate increases first and then decreases,the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution,and the internal reaction of the coating declines.
基金supported by the China Postdoctoral Science Foundation(No.2022M720401)the Postdoctoral Research Foundation of Shunde Innovation School,University of Science and Technology Beijing(No.2022BH007)the National Natural Science Foundation of China(No.52301074).
文摘To enhance the microbiologically influenced corrosion(MIC)resistance of FeCoNiCrMn high entropy alloy(HEAs),a series of Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs were prepared.Microstructural characteristics,corrosion behavior(morphology observation and electrochemical properties),and antimicrobial performance of Fe_(x)Cu_((1−x))CoNiCrMn HEAs were evaluated in a medium inoculated with typical corrosive microorganism Pseudomonas aeruginosa.The aim was to identify copper-containing FeCoNiCrMn HEAs that balance corrosion resistance and antimicrobial properties.Results revealed that all Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs exhibited an FCC(face centered cubic)phase,with significant grain refinement observed in Fe_(0.75)Cu_(0.25)CoNiCrMn HEA.Electrochemical tests indicated that Fe_(0.75)Cu_(0.25)CoNiCrMn HEA demonstrated lower corrosion current density(i_(corr))and pitting potential(E_(pit))compared to other Fe_(x)Cu_((1−x))CoNiCrMn HEAs in P.aeruginosa-inoculated medium,exhibiting superior resistance to MIC.Anti-microbial tests showed that after 14 d of immersion,Fe_(0.75)Cu_(0.25)CoNiCrMn achieved an antibacterial rate of 89.5%,effectively inhibiting the adhesion and biofilm formation of P.aeruginosa,thereby achieving resistance to MIC.
文摘Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosion treated samples were then subjected to high-temperature experiments at 25,300,600,and 900℃,and triaxial compression experiments were conducted in the laboratory.The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality,wave velocity,porosity and compression failure characteristics of the rock.Based on the Lemaitre strain equivalent hypothesis theory,the damage degree of rock material was described by introducing damage variables,and the spatial mobilized plane(SMP)criterion was adopted.The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process,which verified the rationality and reliability of the model parameters.The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage,which had certain practical significance for rock engineering construction.
基金financially supported by the National Natural Science Foundation of China(51971071 and 52075112)Fundamental Research Projects of Science&Technology Innovation and development Plan in Yantai City(2022JCYJ023)。
文摘The in-situ growing approach was utilized in this article to construct the magnesium–aluminum layered double hydroxide(MgAl-LDH)film on the surface of a 1060 aluminum anodized film.To improve the corrosion resistance and friction qualities of aluminum alloy,the MgAl-LDH coating was treated using stearic acid(SA)and thiourea(TU).The aluminum substrate and anodized aluminum film layer corroded to varying degrees after 24 h of immersion in 3.5%(mass)NaCl solution,while the modified hydrotalcite film layer continued to exhibit the same microscopic morphology even after being immersed for 7 d.The results show that the synergistic action of thiourea and stearic acid can effectively improve the corrosion resistance of the MgAl-LDH substrate.The tribological testing reveals that the hydrotalcite film layer and the modified film layer lowered the friction coefficient of the anodized aluminum surface substantially.The results of the simulations and experiments demonstrate that SA forms the dense LDH-TU interlayer film layer by exchanging NO_(3)^(-)ions between TU layers on the one hand and the LDH-SA film layer by adsorption on the surface of LDH on the other.Together,these two processes create LDH-TUSA,which can significantly increase the substrate’s corrosion resistance.This synergistically modified superhydrophobic and retardant hydrotalcite film layer offers a novel approach to the investigation of wear reduction and corrosion protection on the surface of aluminum and its alloys.
基金the financial support for this research by the Australian Research Council (ARC) through the Future Fellowship (FT160100252)the Discovery Project (DP170102557)。
文摘In this study,extrusion was performed on Mg-Zr-Sr-Dy alloys for improving their mechanical,corrosion,and biocompatibility properties.Effects of extrusion and alloying elements on the microstructural characteristics,tensile and compressive strengths,corrosion behavior,and biocompatibility were investigated.The Mg-Zr-Sr-Dy alloys were composed of an α-Mg matrix containing {10■2} extension twins and secondary phases of intermetallic compounds Mg_(17)Sr_(2) and Mg_(2)Dy.Evolution of basal and rare earth(RE) textures was observed in the extruded alloys and an increase in Dy content to 2 wt.% resulted in texture randomization and strengthening of the RE component,mainly due to particle-stimulated nucleation and a change from discontinuous dynamic recrystallization to continuous dynamic recrystallization,which also led to an improved tension-compression yield asymmetry of 0.87.Extrusion of the alloys significantly enhanced their tensile and compressive properties due to improved distribution of alloying elements and formation of textures.Corrosion rates tested by hydrogen evolution testing,potentiodynamic polarization,and electrical impedance spectroscopy showed similar trends for each composition,and the lowest corrosion rate of 3.37 mmy^(-1) was observed for the Mg-1Zr-0.5Sr-1Dy in the potentiodynamic polarization testing.Dy_(2)O_(3) was observed in the inner layers of the Mg(OH)_(2) protective films,whose protective efficacy was confirmed by charge-transfer and film resistances.A comparison among the minimum CRs observed in this study and previously studied as-cast Mg-Zr-Sr-Dy and extruded Mg-Zr-Sr alloys,demonstrates that both the extrusion process and addition of Dy in Mg-Zr-Sr improved the CR.Similarly,extruded Mg-Zr-Sr-Dy alloys showed improved cell viability and adhesion of human osteoblast-like SaOS2 cells due to increased corrosion resistance and enhanced Sr distribution within the Mg matrix.
基金Project(2014TDJH104)supported by Shandong University of Science and Technology(SDUST)Research FundChina+3 种基金Project(2013RCJJ006)supported by Scientific Research Foundation of Shandong University of Science and Technology for Recruited TalentsChinaProject(BS2013CL009)supported by Scientific Research Foundation of Shandong for Outstanding Young ScientistChina
文摘To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.
基金Project(NCET-11-0554)supported by the Program for New Century Excellent Talents in UniversityProject(2011BAE22B04)supportedby the National Key Technology R&D Program of ChinaProject(51271206)supported by the National Natural Science Foundation of China
文摘Mg69Zn27Ca4 alloys with diameters of 1.5, 2 and 3 mm were fabricated using copper mold injection casting method. Microstructural analysis reveals that the alloy with a diameter of 1.5 mm is almost completely composed of amorphous phase. However, with the cooling rate decline, a little α-Mg and MgZn dendrites can be found in the amorphous matrix. Based on the microstructural and tensile results, the ductile dendrites are conceived to be highly responsible for the enhanced compressive strain from 1.3% to 3.1% by increasing the sample diameter from 1.5 mm to 3 mm. In addition, the Mg69Zn27Ca4 alloy with 1.5 mm diameter has the best corrosion properties. The current Mg-based alloys show much better corrosion resistance than the traditionally commercial wrought magnesium alloy ZK60 in simulated sea-water.
基金Project(51374084)supported by the National Natural Science Foundation of ChinaProject supported by the Power Electronics Science and Education Development Program of Delta Environmental&Educational Foundation,ChinaProject(2010K10-08)supported by the Science and Technology Plan(Industrial Research)of Shaanxi Province,China
文摘Long period stacking ordered（LPSO） structure phases were prepared by conventional solidification method in Mg（94）Zn3YxGd（3-x）（x=3,2,1.5,1,mole fraction） alloys,the microstructures,corrosion and compressive mechanical properties of which were investigated,separately.The results reveal that the microstructures of the as-cast Mg（94）Zn3YxGd（3-x） alloys,with n（Zn）/n（Y＋Gd）=1：1,consist of α（Mg） phase,Mg3Zn3RE2（W） phase,Mg（12）ZnRE（14H-LPSO） phase and a few bright cube-shaped Mg-Y-Gd phases.The formation and the distribution of LPSO-phase in the alloys can be influenced by the content of Gd.The volume fraction of 14H-LPSO phase increases first and then decreases with the increase of the Gd content.For the electrochemical impedance spectroscopy（EIS） measurement,a R（Q（R（QR））） model was used to fit the test results in 3.5%（mass fraction） NaCl solution at room temperature.The corrosion current densities of all samples are about 10-（-5） A/cm-2.When x（Gd）≤1%,Mg-Zn-Y-（Gd）alloy shows good corrosion resistance,which is better than that of the commercial AZ91 D magnesium alloy.The corrosion rate increases when the Gd content is higher than 1.5%.At room temperature,the compressive properties of Mg-Zn-Y-（Gd） alloys increase remarkably with the increase of the volume fraction of LPSO phase.In addition,the pinning effect of W-phase and dispersive cube-shaped Mg-Y-Gd phase is beneficial to improving the mechanical properties of as-cast Mg（94）Zn3YxGd（3-x） alloy in deformation process.
