Mg–3Nd–0.2Zn–0.4Zr(NZ30K,wt.%)alloy is a new kind of high-performance metallic biomaterial.The combination of the NZ30K Magnesium(Mg)alloy and selective laser melting(SLM)process seems to be an ideal solution to pr...Mg–3Nd–0.2Zn–0.4Zr(NZ30K,wt.%)alloy is a new kind of high-performance metallic biomaterial.The combination of the NZ30K Magnesium(Mg)alloy and selective laser melting(SLM)process seems to be an ideal solution to produce porous Mg degradable implants.However,the microstructure evolution and mechanical properties of the SLMed NZ30K Mg alloy were not yet studied systematically.Therefore,the fabrication defects,microstructure,and mechanical properties of the SLMed NZ30K alloy under different processing parameters were investigated.The results show that there are two types of fabrication defects in the SLMed NZ30K alloy,gas pores and unfused defects.With the increase of the laser energy density,the porosity sharply decreases to the minimum first and then slightly increases.The minimum porosity is 0.49±0.18%.While the microstructure varies from the large grains with lamellar structure inside under low laser energy density,to the large grains with lamellar structure inside&the equiaxed grains&the columnar grains under middle laser energy density,and further to the fine equiaxed grains&the columnar grains under high laser energy density.The lamellar structure in the large grain is a newly observed microstructure for the NZ30K Mg alloy.Higher laser energy density leads to finer grains,which enhance all the yield strength(YS),ultimate tensile strength(UTS)and elongation,and the best comprehensive mechanical properties obtained are YS of 266±2.1 MPa,UTS of 296±5.2 MPa,with an elongation of 4.9±0.68%.The SLMed NZ30K Mg alloy with a bimodal-grained structure consisting of fine equiaxed grains and coarser columnar grains has better elongation and a yield drop phenomenon.展开更多
Due to their capability of fabricating geometrically complex structures,additive manufacturing(AM)techniques have provided unprecedented opportunities to produce biodegradable metallic implants—especially using Mg al...Due to their capability of fabricating geometrically complex structures,additive manufacturing(AM)techniques have provided unprecedented opportunities to produce biodegradable metallic implants—especially using Mg alloys,which exhibit appropriate mechanical properties and outstanding biocompatibility.However,many challenges hinder the fabrication of AM-processed biodegradable Mg-based implants,such as the difficulty of Mg powder preparation,powder splash,and crack formation during the AM process.In the present work,the challenges of AM-processed Mg components are analyzed and solutions to these challenges are proposed.A novel Mg-based alloy(Mg-Nd-Zn-Zr alloy,JDBM)powder with a smooth surface and good roundness was first synthesized successfully,and the AM parameters for Mg-based alloys were optimized.Based on the optimized parameters,porous JDBM scaffolds with three different architectures(biomimetic,diamond,and gyroid)were then fabricated by selective laser melting(SLM),and their mechanical properties and degradation behavior were evaluated.Finally,the gyroid scaffolds with the best performance were selected for dicalcium phosphate dihydrate(DCPD)coating treatment,which greatly suppressed the degradation rate and increased the cytocompatibility,indicating a promising prospect for clinical application as bone tissue engineering scaffolds.展开更多
The effects of different Zn addition(0,0.2,0.5,1.0 wt%)on the microstructure and mechanical properties of cast Mg-1Nd-1Ce-Zr alloy in as-cast,solution-treated and 200℃peak-aged conditions were studied.Precipitates in...The effects of different Zn addition(0,0.2,0.5,1.0 wt%)on the microstructure and mechanical properties of cast Mg-1Nd-1Ce-Zr alloy in as-cast,solution-treated and 200℃peak-aged conditions were studied.Precipitates in cast Mg-1Nd-1Ce-Zr alloy are significantly modified by the Zn addition.In the Zn-free alloy,the disk-shaped prismatic precipitates and the point-like precipitates are the main strengthening phases.When 0.2 Zn is added,the disk-shaped precipitates are refined and very fine basal precipitates form additionally.When 0.5 Zn is added,the basal precipitates become the main strengthening phase.Further increasing the Zn addition to 1.0%,only spare basal precipitates and point-like precipitates exist.The 0.5 Zn addition alloy has the highest strength at room temperature,whose yield strength,ultimate tensile strength and elongation in T6 condition are 136 MPa,237 MPa and 9%,respectively.展开更多
Based on the hot tearing index|△T/△(fs)^(0.5)|recently proposed by Kou and the thermodynamic calculations of Pandat software,Al,Cu,and Mn elements were picked up and their influence on hot tearing susceptibility of ...Based on the hot tearing index|△T/△(fs)^(0.5)|recently proposed by Kou and the thermodynamic calculations of Pandat software,Al,Cu,and Mn elements were picked up and their influence on hot tearing susceptibility of Mg-x Zn(x=6,8,10,wt%)alloys was studied by experiments.The results indicate that Al addition can significantly reduce the hot tearing susceptibility of Mg-Zn alloys.Either 0.5Cu or 0.3Mn addition individually can reduce the HTS of the Mg-6Zn-(1,4)Al alloys,while adding together increases the susceptibility.The addition of 0.5Cu and 0.3Mn both individually and together increases the HTS of Mg-8/10Zn-1Al alloys.Based on the experimental and calculation results,the index can be modified to|△T/△(fs)^(0.5)|(d)^(2)for more accurate prediction on the hot tearing resistance of Mg-Zn based alloys.Grain refinement significantly improves the hot tearing resistance of Mg-Zn based alloys.展开更多
The microstructure and mechanical properties of cast Mg-9Al-2Sn-xMn(x=0,0.1,0.3 wt.%)alloys in as-cast,solution treated and aged conditions are investigated.The results reveal that Mn addition into Mg-9Al-2Sn alloy le...The microstructure and mechanical properties of cast Mg-9Al-2Sn-xMn(x=0,0.1,0.3 wt.%)alloys in as-cast,solution treated and aged conditions are investigated.The results reveal that Mn addition into Mg-9Al-2Sn alloy leads to the formation of Al8(Mn,Fe)5 phases,the grain refinement and the increase of discontinuous Mg17Al12 precipitates along the grain boundaries.0.1 wt.%Mn addition has an obvious effect on accelerating the aging behavior of Mg-9Al-2Sn alloy at the early aging period up to 8 h,while 0.3 wt.%Mn addition alloy has an comparable aging behavior with the Mn-free alloy.Mn addition has less influence on the fracture behavior of Mg-9Al-2Sn alloy,while the fracture pattern is mainly determined by the thermal conditions.Mg-9Al-2Sn-0.1Mn alloy has the best combination of strength and elongation when aged at 200℃ for 8 h and the yield strength,ultimate tensile strength and elongation are 154 MPa,292MPa and 5%,respectively.展开更多
Magnesium(Mg)alloys that have both antibacterial and osteogenic properties are suitable candidates for orthopedic implants.However,the fabrication of ideal Mg implants suitable for bone repair remains challenging beca...Magnesium(Mg)alloys that have both antibacterial and osteogenic properties are suitable candidates for orthopedic implants.However,the fabrication of ideal Mg implants suitable for bone repair remains challenging because it requires implants with interconnected pore structures and personalized geometric shapes.In this study,we fabricated a porous 3D-printed Mg-Nd-Zn-Zr(denoted as JDBM)implant with suitable mechanical properties using selective laser melting technology.The 3D-printed JDBM implant exhibited cytocompatibility in MC3T3-E1 and RAW267.4 cells and excellent osteoinductivity in vitro.Furthermore,the implant demonstrated excellent antibacterial ratios of 90.0% and 92.1% for methicillin-resistant S.aureus(MRSA)and Escherichia coli,respectively.The 3D-printed JDBM implant prevented MRSA-induced implant-related infection in a rabbit model and showed good in vivo biocompatibility based on the results of histological evaluation,blood tests,and Mg2+deposition detection.In addition,enhanced inflammatory response and TNF-α secretion were observed at the bone-implant interface of the 3D-printed JDBM implants during the early implantation stage.The high Mg^(2+)environment produced by the degradation of 3D-printed JDBM implants could promote M1 phenotype of macrophages(Tnf,iNOS,Ccl3,Ccl4,Ccl5,Cxcl10,and Cxcl2),and enhance the phagocytic ability of macrophages.The enhanced immunoregulatory effect generated by relatively fast Mg^(2+)release and implant degradation during the early implantation stage is a potential antibacterial mechanism of Mg-based implant.Our findings indicate that 3D-printed porous JDBM implants,having both antibacterial property and osteoinductivity,hold potential for future orthopedic applications.展开更多
基金financial supports from the National Natural Science Foundation of China(52130104,51821001)High Technology and Key Development Project of Ningbo,China(2019B10102)。
文摘Mg–3Nd–0.2Zn–0.4Zr(NZ30K,wt.%)alloy is a new kind of high-performance metallic biomaterial.The combination of the NZ30K Magnesium(Mg)alloy and selective laser melting(SLM)process seems to be an ideal solution to produce porous Mg degradable implants.However,the microstructure evolution and mechanical properties of the SLMed NZ30K Mg alloy were not yet studied systematically.Therefore,the fabrication defects,microstructure,and mechanical properties of the SLMed NZ30K alloy under different processing parameters were investigated.The results show that there are two types of fabrication defects in the SLMed NZ30K alloy,gas pores and unfused defects.With the increase of the laser energy density,the porosity sharply decreases to the minimum first and then slightly increases.The minimum porosity is 0.49±0.18%.While the microstructure varies from the large grains with lamellar structure inside under low laser energy density,to the large grains with lamellar structure inside&the equiaxed grains&the columnar grains under middle laser energy density,and further to the fine equiaxed grains&the columnar grains under high laser energy density.The lamellar structure in the large grain is a newly observed microstructure for the NZ30K Mg alloy.Higher laser energy density leads to finer grains,which enhance all the yield strength(YS),ultimate tensile strength(UTS)and elongation,and the best comprehensive mechanical properties obtained are YS of 266±2.1 MPa,UTS of 296±5.2 MPa,with an elongation of 4.9±0.68%.The SLMed NZ30K Mg alloy with a bimodal-grained structure consisting of fine equiaxed grains and coarser columnar grains has better elongation and a yield drop phenomenon.
基金This work was supported by the National Natural Science Foundation of China(51571143)the National Key Research and Development Program of China(2016YFC1102103)+1 种基金the Science and Technology Commission of Shanghai Municipality(19441906300,18441908000,and 17440730700)San-Ming Project of Medicine in Shenzhen(SZSM201612092).
文摘Due to their capability of fabricating geometrically complex structures,additive manufacturing(AM)techniques have provided unprecedented opportunities to produce biodegradable metallic implants—especially using Mg alloys,which exhibit appropriate mechanical properties and outstanding biocompatibility.However,many challenges hinder the fabrication of AM-processed biodegradable Mg-based implants,such as the difficulty of Mg powder preparation,powder splash,and crack formation during the AM process.In the present work,the challenges of AM-processed Mg components are analyzed and solutions to these challenges are proposed.A novel Mg-based alloy(Mg-Nd-Zn-Zr alloy,JDBM)powder with a smooth surface and good roundness was first synthesized successfully,and the AM parameters for Mg-based alloys were optimized.Based on the optimized parameters,porous JDBM scaffolds with three different architectures(biomimetic,diamond,and gyroid)were then fabricated by selective laser melting(SLM),and their mechanical properties and degradation behavior were evaluated.Finally,the gyroid scaffolds with the best performance were selected for dicalcium phosphate dihydrate(DCPD)coating treatment,which greatly suppressed the degradation rate and increased the cytocompatibility,indicating a promising prospect for clinical application as bone tissue engineering scaffolds.
基金This work was supported by National Key Research and Development Program of China(2016YFB0301000&2016YFB0701204)Shanghai Rising-Star Program(15QB1402700)+1 种基金National Natural Science Foundation of China(NSFC)(51671128&51771113)Special Fund of Jiangsu Province for the Transformation of Scientific and Technological Achievements(BA2016039).
文摘The effects of different Zn addition(0,0.2,0.5,1.0 wt%)on the microstructure and mechanical properties of cast Mg-1Nd-1Ce-Zr alloy in as-cast,solution-treated and 200℃peak-aged conditions were studied.Precipitates in cast Mg-1Nd-1Ce-Zr alloy are significantly modified by the Zn addition.In the Zn-free alloy,the disk-shaped prismatic precipitates and the point-like precipitates are the main strengthening phases.When 0.2 Zn is added,the disk-shaped precipitates are refined and very fine basal precipitates form additionally.When 0.5 Zn is added,the basal precipitates become the main strengthening phase.Further increasing the Zn addition to 1.0%,only spare basal precipitates and point-like precipitates exist.The 0.5 Zn addition alloy has the highest strength at room temperature,whose yield strength,ultimate tensile strength and elongation in T6 condition are 136 MPa,237 MPa and 9%,respectively.
基金supported by the National Key Research and Development Program of China(2016YFB0701204)Shang-hai Rising-Star Program(15QB1402700)Special Fund of Jiangsu Province for the Transformation of Scientific and Technological Achievements(BA2016039).
文摘Based on the hot tearing index|△T/△(fs)^(0.5)|recently proposed by Kou and the thermodynamic calculations of Pandat software,Al,Cu,and Mn elements were picked up and their influence on hot tearing susceptibility of Mg-x Zn(x=6,8,10,wt%)alloys was studied by experiments.The results indicate that Al addition can significantly reduce the hot tearing susceptibility of Mg-Zn alloys.Either 0.5Cu or 0.3Mn addition individually can reduce the HTS of the Mg-6Zn-(1,4)Al alloys,while adding together increases the susceptibility.The addition of 0.5Cu and 0.3Mn both individually and together increases the HTS of Mg-8/10Zn-1Al alloys.Based on the experimental and calculation results,the index can be modified to|△T/△(fs)^(0.5)|(d)^(2)for more accurate prediction on the hot tearing resistance of Mg-Zn based alloys.Grain refinement significantly improves the hot tearing resistance of Mg-Zn based alloys.
基金This research work is collaborated by General Motors Global Research and Development(GM R&D),Warren,MI,USA,and Shanghai Jiao Tong University(SJTU),Shanghai,China.Dr P.Fu would like to acknowledge the support of a Specialized Research Fund for the Doctoral Program of Higher Education(20110073120008)a project from Shanghai Science and Technology Committee(12DZ0501700).
文摘The microstructure and mechanical properties of cast Mg-9Al-2Sn-xMn(x=0,0.1,0.3 wt.%)alloys in as-cast,solution treated and aged conditions are investigated.The results reveal that Mn addition into Mg-9Al-2Sn alloy leads to the formation of Al8(Mn,Fe)5 phases,the grain refinement and the increase of discontinuous Mg17Al12 precipitates along the grain boundaries.0.1 wt.%Mn addition has an obvious effect on accelerating the aging behavior of Mg-9Al-2Sn alloy at the early aging period up to 8 h,while 0.3 wt.%Mn addition alloy has an comparable aging behavior with the Mn-free alloy.Mn addition has less influence on the fracture behavior of Mg-9Al-2Sn alloy,while the fracture pattern is mainly determined by the thermal conditions.Mg-9Al-2Sn-0.1Mn alloy has the best combination of strength and elongation when aged at 200℃ for 8 h and the yield strength,ultimate tensile strength and elongation are 154 MPa,292MPa and 5%,respectively.
基金supported by the National Natural Science Foundation of China(81972058,81902194,81902201,and 51821001)National Key R&D Program of China(2016YFC1100600,subproject 2016YFC1100604)+4 种基金Multicenter Clinical Research Project of Shanghai Jiao Tong University School of Medicine,China(DLY201506)High Technology and Key Development Project of Ningbo,China(2019B10102)Shanghai Municipal Key Clinical Specialty,China(shslczdzk06701)National Facility for Translational Medicine(Shanghai),China(TMSZ-2020-207)the Interdisciplinary Program of Shanghai Jiao Tong University,China(YG2019QN2019).
文摘Magnesium(Mg)alloys that have both antibacterial and osteogenic properties are suitable candidates for orthopedic implants.However,the fabrication of ideal Mg implants suitable for bone repair remains challenging because it requires implants with interconnected pore structures and personalized geometric shapes.In this study,we fabricated a porous 3D-printed Mg-Nd-Zn-Zr(denoted as JDBM)implant with suitable mechanical properties using selective laser melting technology.The 3D-printed JDBM implant exhibited cytocompatibility in MC3T3-E1 and RAW267.4 cells and excellent osteoinductivity in vitro.Furthermore,the implant demonstrated excellent antibacterial ratios of 90.0% and 92.1% for methicillin-resistant S.aureus(MRSA)and Escherichia coli,respectively.The 3D-printed JDBM implant prevented MRSA-induced implant-related infection in a rabbit model and showed good in vivo biocompatibility based on the results of histological evaluation,blood tests,and Mg2+deposition detection.In addition,enhanced inflammatory response and TNF-α secretion were observed at the bone-implant interface of the 3D-printed JDBM implants during the early implantation stage.The high Mg^(2+)environment produced by the degradation of 3D-printed JDBM implants could promote M1 phenotype of macrophages(Tnf,iNOS,Ccl3,Ccl4,Ccl5,Cxcl10,and Cxcl2),and enhance the phagocytic ability of macrophages.The enhanced immunoregulatory effect generated by relatively fast Mg^(2+)release and implant degradation during the early implantation stage is a potential antibacterial mechanism of Mg-based implant.Our findings indicate that 3D-printed porous JDBM implants,having both antibacterial property and osteoinductivity,hold potential for future orthopedic applications.
