The diffusible hydrogen contents in precharged (Co,Fe) 3V alloy were measured. It is found that atomic ordering can not promote hydrogen penetration in the (Co,Fe) 3V alloy. The ultimate tensile strength (UTS) and duc...The diffusible hydrogen contents in precharged (Co,Fe) 3V alloy were measured. It is found that atomic ordering can not promote hydrogen penetration in the (Co,Fe) 3V alloy. The ultimate tensile strength (UTS) and ductilities in various condition were also investigated. The results show that the UTS and elongation of disordered alloy are higher than that of ordered one with fixed diffusible hydrogen content and (Co,Fe) 3V alloy with ordered structure is highly susceptible to the embrittlement in hydrogen gas. The factor which may affect the susceptibility to the embrittlement of (Co,Fe) 3V alloy in hydrogen gas is mainly due to that the atomic ordering may accelerate the kinetics of the catalytic reaction for the dissociation of molecular hydrogen into atomic hydrogen. However, it can not be roled out that atomic ordering intensifies planar slip and restricts cross slip at the grain boundaries and enhances the susceptibility of the alloy to hydrogen embrittlement.展开更多
TEM study was made to explore the mechanism of the strain-age hardening of initially-dis- ordered (Co_(78)Fe_(22))_3V,which was found to be attributed to the formation of a special disloca- tion-stacking fault configu...TEM study was made to explore the mechanism of the strain-age hardening of initially-dis- ordered (Co_(78)Fe_(22))_3V,which was found to be attributed to the formation of a special disloca- tion-stacking fault configuration in company with disorder-order transformation-disloca- tions extended to stacking faults on{111}planes and got connected with each other through partial dislocation reaction at intersections of{111}planes,leading to dense networks with cells bounded by stacking fault tetrahedrons.The results also indicated that ordered (Co_(78)Fe_(22))_3V has very low stacking fault energy on{111}planes and relative high and isotropie antiphase boundary energy,which implies that it is most likely to be Lomer-Cottrell locks,not Kear-Wilsdof locks,that are responsible for the high strength at high temperatures of this alloy.展开更多
The effect of multi-pass friction stir processing(FSP)on the tribological properties of conventionally-cast Al−8.5Fe−1.3V−1.7Si(FVS0812)alloy was investigated.The pin-on-disk dry sliding wear tests were conducted at r...The effect of multi-pass friction stir processing(FSP)on the tribological properties of conventionally-cast Al−8.5Fe−1.3V−1.7Si(FVS0812)alloy was investigated.The pin-on-disk dry sliding wear tests were conducted at room temperature under the applied pressures of 0.25,0.50,and 0.75 MPa.The results showed that FSP substantially refined and improved the distribution of coarse¸-Al_(13)Fe4 platelets andα-Al_(12)(Fe,V)_(3)Si intermetallics in the microstructure of alloys and eliminated the intermetallic-related defects.Consequently,the mechanical properties of the alloys,especially their ductility,were improved,which enhanced the stability of the protective tribolayer formed on their worn surfaces.According to the wear test results,the FSPed samples showed improved tribological properties especially at the higher applied pressures.For instance,at the applied pressure of 0.75 MPa,the wear rate and average friction coefficient of four-pass FSPed sample were lower than those of the base as-cast sample by 97%and 52%,respectively.SEM examination of the worn surfaces and wear debris also demonstrated that the wear mechanism changed from severe delamination/abrasion and microcracking of the tribolayer in the as-cast samples to mild delamination/abrasion and minor plastic wear in the FSPed samples.展开更多
The non-isothermal reduction kinetics and mechanism of Fe2O3-NiO composites with different Fe2O3-NiO compacts using carbon monoxide as reductant were investigated. The results show that the reduction degree increases ...The non-isothermal reduction kinetics and mechanism of Fe2O3-NiO composites with different Fe2O3-NiO compacts using carbon monoxide as reductant were investigated. The results show that the reduction degree increases rapidly with increasing the content of NiO, and the presence of NiO also improves the reduction rate of iron oxides. It is found that NiO is preferentially reduced at the beginning of the reactions, and then the metallic Ni acts as a catalyst promoting the reduction rate of iron oxides. It is also observed that the increase of the Ni O content enhances the formation of awaruite(FeNi3) but decreases the percentage of kamacite(Fe,Ni) and taenite(Fe,Ni). The particle size of the materials tends to be uniform during the reduction process due to the presence of metallic nickel, metallic iron and the formation of Fe-Ni alloy. The concentration of CO in the product gas is greater than that of CO2 at the beginning of the reaction and then slows down. The fastest reduction rate of Fe2O3-NiO composites with CO appears at 400-500 °C, and nucleation growth model can be used to elucidate the reduction mechanism. Nucleation growth process is found to be the rate controlling step when the temperature is lower than 1000 °C.展开更多
The isothermal corrosion testing, microscopic examination and the performance of Fe3Si alloy as materials of construction for bath hardware in continuous hot-dipping lines were studied. The corrosion of Fe3Si alloy in...The isothermal corrosion testing, microscopic examination and the performance of Fe3Si alloy as materials of construction for bath hardware in continuous hot-dipping lines were studied. The corrosion of Fe3Si alloy in molten zinc was controlled by attacking the grain boundaries preferentially. Aluminum reacted with iron of Fe3Si alloy firstly while the samples were immersed in molten zinc, although aluminum contents in the molten zinc were very low. The phase of reaction product was thought to be Fe2Al5. The corrosion rate of the Fe3Si alloy in molten zinc was determined to be approximately 2.9×10^-3 mm/h, therefore the liquid zinc corrosion resistance of Fe3Si alloy was very weak.展开更多
The influence of different lubricants on the deformation behaviour of IN 718 alloy was studied. The results show that, with the improvement of lubrication condition, the deformation of the alloy tends to be homogeneou...The influence of different lubricants on the deformation behaviour of IN 718 alloy was studied. The results show that, with the improvement of lubrication condition, the deformation of the alloy tends to be homogeneous, and the resistance of deformation decreases. Consequently, FR 2 glass lubricant is considered to be an ideal choice when the relationship between stress and strain of IN 718 alloy is measured by means of hot compression experiment.展开更多
By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L...By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.展开更多
The cyclic voltammetry, chronopotentiometry and chronoamperometry were used to study the behaviors of Fe 2+ on Pt, Cu, Ag and Ti electrodes in urea NaBr melt at 373 K. Electroreduction of Fe 2+ to metallic ...The cyclic voltammetry, chronopotentiometry and chronoamperometry were used to study the behaviors of Fe 2+ on Pt, Cu, Ag and Ti electrodes in urea NaBr melt at 373 K. Electroreduction of Fe 2+ to metallic Fe is irreversible in one step. The exchange current density determined on Ti electrode is 2 68×10 -5 A·cm -2 . Sm 3+ does not reduce to Sm alone, but can be inductively codeposited with Fe 2+ . Sm Fe alloy film contained over 90% Sm (mass fraction) can be obtained by potentiostatic electrolysis and galvanostatic electrolysis on Cu substrate. The Sm content in the alloy is related to the cathode potential, current density and the Sm 3+ /Fe 2+ molar ratio. The surface state of the Sm Fe deposit was studied by scanning electron microscopy.展开更多
The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement...The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement. Ti50Ni47Fe3 alloy has different deformation behaviors at different temperature ranges, the deformation curves in different temperature range can be classified into four kinds. The start temperature of recovery increases with the increase of pre-strain. There exists an optimal deformation condition, at which the specimen exhibits maximum free recovery strain. With increasing pre-strain the recovery stress increases and reaches the maximum at 8% pre-strain. R-phase to parent transition offered about 0.2% recovery strain. With pre-strain increasing the recovery stress increases and reaches to the maximum at 8% pre-strain. The recovery stress is corresponding with the critical stress of stress-induced martensitic transformation.展开更多
Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide(CTAB)-modified Watt's nickel bath with Fe2O3 particles dispersed in it.The effects of the plating parameters on the chemica...Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide(CTAB)-modified Watt's nickel bath with Fe2O3 particles dispersed in it.The effects of the plating parameters on the chemical composition,structural and morphological characteristics of the electrodeposited Ni-Co-Fe2O3 composite coatings were investigated by energy dispersive X-ray(EDS) spectroscopy,X-ray diffractometry(XRD) and scanning electron microscopy(SEM).The results reveal that Fe2O3 particles can be codeposited in the Ni-Co matrix.The codeposition of Fe2O3 particles with Ni-Co is favoured at high Fe2O3 particle concentration and medium stirring,and the deposition of Co is favoured at high concentration of CTAB.Moreover,the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed <220> preferred orientation.Composites with high concentration of embedded particles exhibit a preferred crystal orientation of <111>.The more the embedded Fe2O3 particles in the metallic matrix,the smaller the sizes of the crystallite for the composite deposits.展开更多
Superconducting (SC) in equal molar NbTaTiZr-based high-entropy alloys (HEAs) that were added with Fe, Ge, Hf, Si, and/or V was observed. According to investigation on crystal structure, composition, and the relations...Superconducting (SC) in equal molar NbTaTiZr-based high-entropy alloys (HEAs) that were added with Fe, Ge, Hf, Si, and/or V was observed. According to investigation on crystal structure, composition, and the relationship between critical temperature and e/a ratio, as indicated in Matthias’ empirical rule, the main superconducting phase was that enriched with Nb and Ta. The coherence length (ξ) that was calculated from the carrier density reveals that ξvalue has the same order of magnitude of several hundreds of Angstroms as those binary Nb-Ti and Nb-Zr alloys showed.展开更多
The atomic scale computer simulation for initial precipitation mechanism of Ni75Al6V19 alloy was carried out for the first time by employing the microscopic diffusion equation. The initial precipitation process was in...The atomic scale computer simulation for initial precipitation mechanism of Ni75Al6V19 alloy was carried out for the first time by employing the microscopic diffusion equation. The initial precipitation process was invest igated throughsimulating the atomic pictures and calculating the order parameters of the two kinds of ordered phases. Simulationresults show that the γ′ordered phase precipitated earlier than θ ordered phase by congruent ordering+spinodal decomposition mechanism and thus produced a nonstoicheometric γ′ single ordered phase. Then, the nonstoichiometricθ phase precipitated by a non-classical nucleation and growth mechanism at the APBS of γ′ phase.展开更多
文摘The diffusible hydrogen contents in precharged (Co,Fe) 3V alloy were measured. It is found that atomic ordering can not promote hydrogen penetration in the (Co,Fe) 3V alloy. The ultimate tensile strength (UTS) and ductilities in various condition were also investigated. The results show that the UTS and elongation of disordered alloy are higher than that of ordered one with fixed diffusible hydrogen content and (Co,Fe) 3V alloy with ordered structure is highly susceptible to the embrittlement in hydrogen gas. The factor which may affect the susceptibility to the embrittlement of (Co,Fe) 3V alloy in hydrogen gas is mainly due to that the atomic ordering may accelerate the kinetics of the catalytic reaction for the dissociation of molecular hydrogen into atomic hydrogen. However, it can not be roled out that atomic ordering intensifies planar slip and restricts cross slip at the grain boundaries and enhances the susceptibility of the alloy to hydrogen embrittlement.
文摘TEM study was made to explore the mechanism of the strain-age hardening of initially-dis- ordered (Co_(78)Fe_(22))_3V,which was found to be attributed to the formation of a special disloca- tion-stacking fault configuration in company with disorder-order transformation-disloca- tions extended to stacking faults on{111}planes and got connected with each other through partial dislocation reaction at intersections of{111}planes,leading to dense networks with cells bounded by stacking fault tetrahedrons.The results also indicated that ordered (Co_(78)Fe_(22))_3V has very low stacking fault energy on{111}planes and relative high and isotropie antiphase boundary energy,which implies that it is most likely to be Lomer-Cottrell locks,not Kear-Wilsdof locks,that are responsible for the high strength at high temperatures of this alloy.
文摘The effect of multi-pass friction stir processing(FSP)on the tribological properties of conventionally-cast Al−8.5Fe−1.3V−1.7Si(FVS0812)alloy was investigated.The pin-on-disk dry sliding wear tests were conducted at room temperature under the applied pressures of 0.25,0.50,and 0.75 MPa.The results showed that FSP substantially refined and improved the distribution of coarse¸-Al_(13)Fe4 platelets andα-Al_(12)(Fe,V)_(3)Si intermetallics in the microstructure of alloys and eliminated the intermetallic-related defects.Consequently,the mechanical properties of the alloys,especially their ductility,were improved,which enhanced the stability of the protective tribolayer formed on their worn surfaces.According to the wear test results,the FSPed samples showed improved tribological properties especially at the higher applied pressures.For instance,at the applied pressure of 0.75 MPa,the wear rate and average friction coefficient of four-pass FSPed sample were lower than those of the base as-cast sample by 97%and 52%,respectively.SEM examination of the worn surfaces and wear debris also demonstrated that the wear mechanism changed from severe delamination/abrasion and microcracking of the tribolayer in the as-cast samples to mild delamination/abrasion and minor plastic wear in the FSPed samples.
基金Projects(51304091,U1302274)supported by the National Natural Science Foundation of ChinaProjects(2013FD009,2013FZ007)supported by Applied Basic Research Program of Yunnan Province,ChinaProject(2012HB009)supported by the Candidate Talents Training Fund of Yunnan Province,China
文摘The non-isothermal reduction kinetics and mechanism of Fe2O3-NiO composites with different Fe2O3-NiO compacts using carbon monoxide as reductant were investigated. The results show that the reduction degree increases rapidly with increasing the content of NiO, and the presence of NiO also improves the reduction rate of iron oxides. It is found that NiO is preferentially reduced at the beginning of the reactions, and then the metallic Ni acts as a catalyst promoting the reduction rate of iron oxides. It is also observed that the increase of the Ni O content enhances the formation of awaruite(FeNi3) but decreases the percentage of kamacite(Fe,Ni) and taenite(Fe,Ni). The particle size of the materials tends to be uniform during the reduction process due to the presence of metallic nickel, metallic iron and the formation of Fe-Ni alloy. The concentration of CO in the product gas is greater than that of CO2 at the beginning of the reaction and then slows down. The fastest reduction rate of Fe2O3-NiO composites with CO appears at 400-500 °C, and nucleation growth model can be used to elucidate the reduction mechanism. Nucleation growth process is found to be the rate controlling step when the temperature is lower than 1000 °C.
基金This work was financially supported by the National Natural Science Foundation of China (No.50274005).
文摘The isothermal corrosion testing, microscopic examination and the performance of Fe3Si alloy as materials of construction for bath hardware in continuous hot-dipping lines were studied. The corrosion of Fe3Si alloy in molten zinc was controlled by attacking the grain boundaries preferentially. Aluminum reacted with iron of Fe3Si alloy firstly while the samples were immersed in molten zinc, although aluminum contents in the molten zinc were very low. The phase of reaction product was thought to be Fe2Al5. The corrosion rate of the Fe3Si alloy in molten zinc was determined to be approximately 2.9×10^-3 mm/h, therefore the liquid zinc corrosion resistance of Fe3Si alloy was very weak.
文摘The influence of different lubricants on the deformation behaviour of IN 718 alloy was studied. The results show that, with the improvement of lubrication condition, the deformation of the alloy tends to be homogeneous, and the resistance of deformation decreases. Consequently, FR 2 glass lubricant is considered to be an ideal choice when the relationship between stress and strain of IN 718 alloy is measured by means of hot compression experiment.
文摘By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.
文摘The cyclic voltammetry, chronopotentiometry and chronoamperometry were used to study the behaviors of Fe 2+ on Pt, Cu, Ag and Ti electrodes in urea NaBr melt at 373 K. Electroreduction of Fe 2+ to metallic Fe is irreversible in one step. The exchange current density determined on Ti electrode is 2 68×10 -5 A·cm -2 . Sm 3+ does not reduce to Sm alone, but can be inductively codeposited with Fe 2+ . Sm Fe alloy film contained over 90% Sm (mass fraction) can be obtained by potentiostatic electrolysis and galvanostatic electrolysis on Cu substrate. The Sm content in the alloy is related to the cathode potential, current density and the Sm 3+ /Fe 2+ molar ratio. The surface state of the Sm Fe deposit was studied by scanning electron microscopy.
文摘The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement. Ti50Ni47Fe3 alloy has different deformation behaviors at different temperature ranges, the deformation curves in different temperature range can be classified into four kinds. The start temperature of recovery increases with the increase of pre-strain. There exists an optimal deformation condition, at which the specimen exhibits maximum free recovery strain. With increasing pre-strain the recovery stress increases and reaches the maximum at 8% pre-strain. R-phase to parent transition offered about 0.2% recovery strain. With pre-strain increasing the recovery stress increases and reaches to the maximum at 8% pre-strain. The recovery stress is corresponding with the critical stress of stress-induced martensitic transformation.
基金Project(2005CB623703) supported by the National Key Basic Research Program of ChinaProject(50474051) supported by the National Natural Science Foundation of China+2 种基金Project(CX2009B032) supported by Innovation Foundation for Postgraduate of Hunan Province of China Project(ZKJ2009024) supported by the Precious Apparatus Open Share Foundation of Central South University, ChinaProject(2009ybfz02) supported by Excellent Doctor Support Fund of Central South University,China
文摘Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide(CTAB)-modified Watt's nickel bath with Fe2O3 particles dispersed in it.The effects of the plating parameters on the chemical composition,structural and morphological characteristics of the electrodeposited Ni-Co-Fe2O3 composite coatings were investigated by energy dispersive X-ray(EDS) spectroscopy,X-ray diffractometry(XRD) and scanning electron microscopy(SEM).The results reveal that Fe2O3 particles can be codeposited in the Ni-Co matrix.The codeposition of Fe2O3 particles with Ni-Co is favoured at high Fe2O3 particle concentration and medium stirring,and the deposition of Co is favoured at high concentration of CTAB.Moreover,the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed <220> preferred orientation.Composites with high concentration of embedded particles exhibit a preferred crystal orientation of <111>.The more the embedded Fe2O3 particles in the metallic matrix,the smaller the sizes of the crystallite for the composite deposits.
文摘Superconducting (SC) in equal molar NbTaTiZr-based high-entropy alloys (HEAs) that were added with Fe, Ge, Hf, Si, and/or V was observed. According to investigation on crystal structure, composition, and the relationship between critical temperature and e/a ratio, as indicated in Matthias’ empirical rule, the main superconducting phase was that enriched with Nb and Ta. The coherence length (ξ) that was calculated from the carrier density reveals that ξvalue has the same order of magnitude of several hundreds of Angstroms as those binary Nb-Ti and Nb-Zr alloys showed.
基金This work was supported by the National Natural Science Foundation of China (Grant No.50071046)
文摘The atomic scale computer simulation for initial precipitation mechanism of Ni75Al6V19 alloy was carried out for the first time by employing the microscopic diffusion equation. The initial precipitation process was invest igated throughsimulating the atomic pictures and calculating the order parameters of the two kinds of ordered phases. Simulationresults show that the γ′ordered phase precipitated earlier than θ ordered phase by congruent ordering+spinodal decomposition mechanism and thus produced a nonstoicheometric γ′ single ordered phase. Then, the nonstoichiometricθ phase precipitated by a non-classical nucleation and growth mechanism at the APBS of γ′ phase.
