Biomedical materials may suffer from stress-induced corrosion when performing as implant materials at load-bearing sites, bringing about variations in the microstructure, corrosion resistance, and mechanical propertie...Biomedical materials may suffer from stress-induced corrosion when performing as implant materials at load-bearing sites, bringing about variations in the microstructure, corrosion resistance, and mechanical properties. In this study, the corrosion behavior and mechanical properties of an extruded Mg-4Li-1Ca alloy were investigated under different micro-compressive stresses (0-6 MPa) using a novel homemade loading device. Under 0-3 MPa of micro-compressive stress, the strong basal texture of extruded Mg-4Li1Ca alloys was weakened and the internal stress gradient stimulated grain boundary migration to induce grain growth. Meanwhile, increased stress resulted in the precipitation of second-phase particles and the accumulation of residual stress, accelerating the corrosion rate due to preferential corrosion. However, with increasing stress, the volume fraction of the second phase increased, becoming the dominant factor controlling the corrosion rate, and residual stress was released for samples under 4.5-6 MPa of microcompressive stress. Hence, surface corrosion product films rapidly formed and served as effective physical barriers, weakening the microstructural effect on the corrosion behavior. The yield strength of Mg-4Li-1Ca alloy reached 95.48 MPa under 3 MPa of micro-compressive stress owing to the dual effects of precipitation strengthening and shear-band strengthening. The relationships between microstructure, corrosion behavior, and mechanical property provide a theoretical foundation for understanding the degradation characteristics of the Mg-4Li-1Ca alloy under physiological loading and practical application.展开更多
The effects of Y on the microstructure and mechanical properties of Mg-6Zn-lMn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mecha...The effects of Y on the microstructure and mechanical properties of Mg-6Zn-lMn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mechanical properties of Mg-6Zn-lMn alloy. Varied phases compositions, including Mg7Zn3, I-phase (Mg3YZn6), W-phase (Mg3Y2Zn3) and X-phase (MgI2YZn), are obtained by adjusting the Zn to Y mass ratio. Mn element exists as the fine Mn particles, which are well distributed in the alloy. Thermal analysis and microstructure observation reveal that the phase stability follows the trend of X〉W〉/〉MgTZn3. In addition, Y can improve the mechanical properties of Mg-Zn-Mn alloy significantly, and the alloy with Y content of 6.09% has the best mechanical properties. The high strength is mainly due to the strengthening by the grain size refinement, dispersion strengthening by fine Mn particles, and introduction of the Mg-Zn-Y ternary phases.展开更多
(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))_(100-x)Sn_(x)(x=3,5,and 7;at%)high-entropy alloys(HEAs)with good mechanical properties,corrosion resistance,and biocompatibility were developed as potential biomaterials.The ...(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))_(100-x)Sn_(x)(x=3,5,and 7;at%)high-entropy alloys(HEAs)with good mechanical properties,corrosion resistance,and biocompatibility were developed as potential biomaterials.The effects of Sn additions on the microstructure and properties of the HEAs were investigated.The(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))_(100-x)Sn_(x) with x=3 at%exhibited the single body-centered-cubic(BCC)structure.The HEAs with the further increased Sn contents of x=5 at%and 7 at%were composed of a BCC phase and a hexagonal-close-packed(HCP)-(Sn,Zr)ordered phase.The addition of Sn improved the compres-sive yield strengths and hardness of the HEAs to 1068-1259 MPa and HV 315-HV 390,respectively.These HEAs also possessed relatively low Young's moduli of 80-91 GPa.Among the present Ti-Zr-Hf-Nb-Ta-Sn HEAs,the(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))97Sn3 HEA exhibited the good combination of high yield strength of~1068 MPa,relatively low Young's modulus of 80 GPa,and good plasticity(~45%).The HEAs also possess good bio-corrosion resistance and biocompatibility,parallel to the Ti-6Al-4V alloy.The Ti-Zr-Hf-Nb-Ta-Sn HEAs with the integration of the high yield strength,relatively low Young's modulus,and good corrosion resistance and bio-compatibility are promising for biomedical applications.展开更多
The effects of thermal treatments on the structure, mechanical properties, wear resistance, and in vitro corrosion protection in artificial saliva(AS) were investigated for a newly developed Ti20 Nb13 Zr(TNZ) alloy. X...The effects of thermal treatments on the structure, mechanical properties, wear resistance, and in vitro corrosion protection in artificial saliva(AS) were investigated for a newly developed Ti20 Nb13 Zr(TNZ) alloy. XRD and SEM analyses were used for structural and microstructural analysis. The in vitro corrosion properties of the samples were investigated using electrochemical impedance spectroscopy and linear polarization resistance techniques up to an immersion time of 168 h. The tribological characteristics were evaluated with a linear reciprocating tribometer. SEM analysis showed that solution treatment and aging influenced the size and distribution of α phase. The air-cooled and aged samples exhibited the highest microhardness and macrohardness, for which the wear resistances were 25% and 30% higher than that of the untreated sample, respectively. The cooling rate significantly influenced the corrosion resistance of the TNZ samples. The treated samples showed a reduced corrosion rate(50%) for long immersion time up to 168 h in AS. The furnace-cooled and aged samples exhibited the highest corrosion resistance after 168 h of immersion in AS. Among the treated samples, the aged sample showed enhanced mechanical properties, wear behavior, and in vitro corrosion resistance in AS.展开更多
A new Gum-type alloy(Ti–Nb–Zr–Fe–O) in which Fe is used instead of Ta was subjected to a particular thermomechanical processing scheme to assess whether its mechanical characteristics(fine ?-grains with high stren...A new Gum-type alloy(Ti–Nb–Zr–Fe–O) in which Fe is used instead of Ta was subjected to a particular thermomechanical processing scheme to assess whether its mechanical characteristics(fine ?-grains with high strength and low modulus) render it suitable as a biomedical implant material. After a homogenization treatment followed by cold-rolling with 50% reduction, the specimens were subjected to one of three different recrystallization treatments at 1073, 1173, and 1273 K. The structural and mechanical properties of all of the treated specimens were analyzed. The mechanical characterization included tensile tests, microhardness determinations, and fractography by scanning electron microscopy. The possible deformation mechanisms were discussed using the Bo – Md diagram. By correlating all of the experimental results, we concluded that the most promising processing variant corresponds to recrystallization at 1073 K, which can provide suitable mechanical characteristics for this type of alloys: high yield and ultimate tensile strengths(1038 and 1083 MPa, respectively), a low modulus of elasticity(62 GPa), and fine crystalline grain size(approximately 50 ?m).展开更多
In order to expand the application horizon of Ti-Zr based alloys,the influence of Nb content on phase composition,microstructural evolution and biomechanical properties is systematically studied.The phase and microstr...In order to expand the application horizon of Ti-Zr based alloys,the influence of Nb content on phase composition,microstructural evolution and biomechanical properties is systematically studied.The phase and microstructural characterization of the as-cast alloys is carried out by X-ray diffraction,optical microscopy and transmission electron microscopy.The results reveal that Nb-containing Ti-Zr alloys transformed from single a phase→α+α"+β phase single β phase double β phases with increasing Nb content.In the case of β-type alloys,the addition of Nb improves the bonding energy between atoms,reduces the grain size,increases the elastic modulus,improves the yield strength and renders superior work-hardening behavior.Moreover,the current study provides mechanistic insights into microstructural evolution and strengthening of Nb-containing Ti-Zr alloys with increasing Nb content.Herein,the addition of 5 at.% Nb resulted in an abnormal work hardening during compression deformation under the synergistic influence of stress-induced martensite transformation of β phase and stress-induced twinning of α phase.Moreover,the biomechanical properties are evaluated to demonstrate the potential of Nb-containing Ti-Zr alloys in biological applications.展开更多
There is an increasing interest in the development of magnesium alloys both for industrial and biomedical applications. Industrial interest in magnesium alloys is based on strong demand of weight reduction of transpor...There is an increasing interest in the development of magnesium alloys both for industrial and biomedical applications. Industrial interest in magnesium alloys is based on strong demand of weight reduction of transportation vehicles for better fuel efficiency, so higher strength, and better ductility and corrosion resistance are required. Nevertheless, biomedical magnesium alloys require appropriate mechanical properties, suitable degradation rate in physiological environment, and what is most important, biosafety to human body. Rather than simply apply commercial magnesium alloys to biomedical field, new alloys should be designed from the point of view of nutriology and toxicology. This article provides a review of state-of-the-art of magnesium alloy implants and devices for orthopedic, cardiovascular and tissue engineering applications. Advances in new alloy design, novel structure design and surface modification are overviewed. The factors that influence the corrosion behavior of magnesium alloys are discussed and the strategy in the future development of biomedical magnesium alloys is proposed.展开更多
Mg-Li based alloys hold much attention as potential biomedical materials due to their excellent ductility. A reduced mechanical strength and concern for biocompatibility are exhibited for Mg-Li binary alloys due to th...Mg-Li based alloys hold much attention as potential biomedical materials due to their excellent ductility. A reduced mechanical strength and concern for biocompatibility are exhibited for Mg-Li binary alloys due to the presence of Li element. Addition of the Ca element into Mg-Li alloys leads to an improvement in mechanical strength and biocompatibility.In the present work, the microstructure, mechanical property and corrosion behaviors of three kinds(α, α+β, β) of as-extruded Mg-Li(1, 9 and 15 wt.%)-1 Ca alloys were investigated using optical microscope, X-ray diffraction(XRD), tensile,immersion and electrochemical polarization measurements.In vitro biocompatibility was evaluated by cytotoxicity assays,hemolysis and four coagluation tests. The results indicated that the Mg-1 Li-1 Ca and Mg-15 Li-1 Ca alloys were characterized by α-Mg and β-Li phases besides Mg2 Ca particles, respectively; while the Mg-9 Li-1 Ca by dual(α-Mg+β-Li) phase together with Mg2 Ca phase. The Mg-1 Li-1 Ca alloy had the highest ultimate tensile strength(UTS) and yield strength(YS)and the lowest elongation(EL) to failure(10.1±1.24%) as well.The EL for the Mg-9 Li-1 Ca alloy was the highest(52.2±0.01%).The long-term immersion tests revealed a decrease in corrosion resistance with increasing Li content. The results of cytotoxicity assays clearly showed that the Mg-Li-Ca alloys demonstrated no toxicity to L-929 cells in 10% concentration of extracts. The Mg-1 Li-1 Ca alloy also exhibited an acceptable hemolysis ratio. The results of four coagulation tests designated no sign of thrombogenicity for the Mg-Li-Ca alloys except for the Mg-15 Li-1 Ca alloy.展开更多
基金support of the National Natural Science Foundation of China(Grant Nos.52071191,52201077)the Natural Science Foundation of Shandong Province(Grant No.ZR2022QE191).
文摘Biomedical materials may suffer from stress-induced corrosion when performing as implant materials at load-bearing sites, bringing about variations in the microstructure, corrosion resistance, and mechanical properties. In this study, the corrosion behavior and mechanical properties of an extruded Mg-4Li-1Ca alloy were investigated under different micro-compressive stresses (0-6 MPa) using a novel homemade loading device. Under 0-3 MPa of micro-compressive stress, the strong basal texture of extruded Mg-4Li1Ca alloys was weakened and the internal stress gradient stimulated grain boundary migration to induce grain growth. Meanwhile, increased stress resulted in the precipitation of second-phase particles and the accumulation of residual stress, accelerating the corrosion rate due to preferential corrosion. However, with increasing stress, the volume fraction of the second phase increased, becoming the dominant factor controlling the corrosion rate, and residual stress was released for samples under 4.5-6 MPa of microcompressive stress. Hence, surface corrosion product films rapidly formed and served as effective physical barriers, weakening the microstructural effect on the corrosion behavior. The yield strength of Mg-4Li-1Ca alloy reached 95.48 MPa under 3 MPa of micro-compressive stress owing to the dual effects of precipitation strengthening and shear-band strengthening. The relationships between microstructure, corrosion behavior, and mechanical property provide a theoretical foundation for understanding the degradation characteristics of the Mg-4Li-1Ca alloy under physiological loading and practical application.
基金Project(2007CB613700)supported by the National Basic Research Program of ChinaProject(2011BAE22B01-3)supported by the National Key Technologies R&D Program of China+1 种基金Project(2010DFR50010,2008DFR50040)supported by the International Scientific and Technological Cooperation Program of Ministry of Science and Technology of ChinaProject(CSTC,2010AA4048)supported by Chongqing Science and Technology Commission,China
文摘The effects of Y on the microstructure and mechanical properties of Mg-6Zn-lMn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mechanical properties of Mg-6Zn-lMn alloy. Varied phases compositions, including Mg7Zn3, I-phase (Mg3YZn6), W-phase (Mg3Y2Zn3) and X-phase (MgI2YZn), are obtained by adjusting the Zn to Y mass ratio. Mn element exists as the fine Mn particles, which are well distributed in the alloy. Thermal analysis and microstructure observation reveal that the phase stability follows the trend of X〉W〉/〉MgTZn3. In addition, Y can improve the mechanical properties of Mg-Zn-Mn alloy significantly, and the alloy with Y content of 6.09% has the best mechanical properties. The high strength is mainly due to the strengthening by the grain size refinement, dispersion strengthening by fine Mn particles, and introduction of the Mg-Zn-Y ternary phases.
基金financially supported by the National Natural Science Foundation of China (Nos. 51971007 and 51701008)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities (No. B17002)support from the National Science Foundation (Nos. DMR-1611180 and 1809640) with program directors, Drs. J. Yang, G. Shiflet, and D. Farkas
文摘(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))_(100-x)Sn_(x)(x=3,5,and 7;at%)high-entropy alloys(HEAs)with good mechanical properties,corrosion resistance,and biocompatibility were developed as potential biomaterials.The effects of Sn additions on the microstructure and properties of the HEAs were investigated.The(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))_(100-x)Sn_(x) with x=3 at%exhibited the single body-centered-cubic(BCC)structure.The HEAs with the further increased Sn contents of x=5 at%and 7 at%were composed of a BCC phase and a hexagonal-close-packed(HCP)-(Sn,Zr)ordered phase.The addition of Sn improved the compres-sive yield strengths and hardness of the HEAs to 1068-1259 MPa and HV 315-HV 390,respectively.These HEAs also possessed relatively low Young's moduli of 80-91 GPa.Among the present Ti-Zr-Hf-Nb-Ta-Sn HEAs,the(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))97Sn3 HEA exhibited the good combination of high yield strength of~1068 MPa,relatively low Young's modulus of 80 GPa,and good plasticity(~45%).The HEAs also possess good bio-corrosion resistance and biocompatibility,parallel to the Ti-6Al-4V alloy.The Ti-Zr-Hf-Nb-Ta-Sn HEAs with the integration of the high yield strength,relatively low Young's modulus,and good corrosion resistance and bio-compatibility are promising for biomedical applications.
基金funding support providing by King Fahd University of Petroleum & Minerals through Project (SR161015)。
文摘The effects of thermal treatments on the structure, mechanical properties, wear resistance, and in vitro corrosion protection in artificial saliva(AS) were investigated for a newly developed Ti20 Nb13 Zr(TNZ) alloy. XRD and SEM analyses were used for structural and microstructural analysis. The in vitro corrosion properties of the samples were investigated using electrochemical impedance spectroscopy and linear polarization resistance techniques up to an immersion time of 168 h. The tribological characteristics were evaluated with a linear reciprocating tribometer. SEM analysis showed that solution treatment and aging influenced the size and distribution of α phase. The air-cooled and aged samples exhibited the highest microhardness and macrohardness, for which the wear resistances were 25% and 30% higher than that of the untreated sample, respectively. The cooling rate significantly influenced the corrosion resistance of the TNZ samples. The treated samples showed a reduced corrosion rate(50%) for long immersion time up to 168 h in AS. The furnace-cooled and aged samples exhibited the highest corrosion resistance after 168 h of immersion in AS. Among the treated samples, the aged sample showed enhanced mechanical properties, wear behavior, and in vitro corrosion resistance in AS.
基金supported by a grant of the Romanian National Authority for Scientific Research, Executive Unity for Higher Education Financing, Research, Development and Innovation, Collaborative Project (2014–2016) (No.213/ 2014)
文摘A new Gum-type alloy(Ti–Nb–Zr–Fe–O) in which Fe is used instead of Ta was subjected to a particular thermomechanical processing scheme to assess whether its mechanical characteristics(fine ?-grains with high strength and low modulus) render it suitable as a biomedical implant material. After a homogenization treatment followed by cold-rolling with 50% reduction, the specimens were subjected to one of three different recrystallization treatments at 1073, 1173, and 1273 K. The structural and mechanical properties of all of the treated specimens were analyzed. The mechanical characterization included tensile tests, microhardness determinations, and fractography by scanning electron microscopy. The possible deformation mechanisms were discussed using the Bo – Md diagram. By correlating all of the experimental results, we concluded that the most promising processing variant corresponds to recrystallization at 1073 K, which can provide suitable mechanical characteristics for this type of alloys: high yield and ultimate tensile strengths(1038 and 1083 MPa, respectively), a low modulus of elasticity(62 GPa), and fine crystalline grain size(approximately 50 ?m).
基金the National Natural Science Foundation of China(Grant no.51531005/51827801/51671166)。
文摘In order to expand the application horizon of Ti-Zr based alloys,the influence of Nb content on phase composition,microstructural evolution and biomechanical properties is systematically studied.The phase and microstructural characterization of the as-cast alloys is carried out by X-ray diffraction,optical microscopy and transmission electron microscopy.The results reveal that Nb-containing Ti-Zr alloys transformed from single a phase→α+α"+β phase single β phase double β phases with increasing Nb content.In the case of β-type alloys,the addition of Nb improves the bonding energy between atoms,reduces the grain size,increases the elastic modulus,improves the yield strength and renders superior work-hardening behavior.Moreover,the current study provides mechanistic insights into microstructural evolution and strengthening of Nb-containing Ti-Zr alloys with increasing Nb content.Herein,the addition of 5 at.% Nb resulted in an abnormal work hardening during compression deformation under the synergistic influence of stress-induced martensite transformation of β phase and stress-induced twinning of α phase.Moreover,the biomechanical properties are evaluated to demonstrate the potential of Nb-containing Ti-Zr alloys in biological applications.
基金Projects(52071339, 51671218) supported by the National Natural Science Foundation of ChinaProject(2020JJ4739) supported by the Natural Science Foundation of Hunan Province,ChinaProject(201009-K) supported by the Guangxi Key Laboratory of Information Materials (Guilin University of Electronic Technology),China。
基金supported by the National Basic Research Program of China(973 Program)(Nos.2012CB619102 and 2012CB619100)the National Science Fund for Distinguished Young Scholars(No.51225101)+4 种基金the National Natural Science Foundation of China(No.31170909)the Research Fund for the Doctoral Program of Higher Education(No.20100001110011) the Natural Science Foundation of Heilongjiang Province(No. ZD201012)the Project for Supervisor of Excellent Doctoral Dissertation of Beijing(No.20121000101)the Guangdong Province Innovation R&D Team Project(No.201001 C0104669453)
文摘There is an increasing interest in the development of magnesium alloys both for industrial and biomedical applications. Industrial interest in magnesium alloys is based on strong demand of weight reduction of transportation vehicles for better fuel efficiency, so higher strength, and better ductility and corrosion resistance are required. Nevertheless, biomedical magnesium alloys require appropriate mechanical properties, suitable degradation rate in physiological environment, and what is most important, biosafety to human body. Rather than simply apply commercial magnesium alloys to biomedical field, new alloys should be designed from the point of view of nutriology and toxicology. This article provides a review of state-of-the-art of magnesium alloy implants and devices for orthopedic, cardiovascular and tissue engineering applications. Advances in new alloy design, novel structure design and surface modification are overviewed. The factors that influence the corrosion behavior of magnesium alloys are discussed and the strategy in the future development of biomedical magnesium alloys is proposed.
基金supported by the National Natural Science Foundation of China (51571134)the Scientific Research Foundation of Shandong University of Science and Technology (SDUST) for Recruited Talents (2013RCJJ006)+1 种基金SDUST Research Fund (2014TDJH104)Joint Innovative Center for Safe and Effective Mining Technology and Equipment of Coal Resources
文摘Mg-Li based alloys hold much attention as potential biomedical materials due to their excellent ductility. A reduced mechanical strength and concern for biocompatibility are exhibited for Mg-Li binary alloys due to the presence of Li element. Addition of the Ca element into Mg-Li alloys leads to an improvement in mechanical strength and biocompatibility.In the present work, the microstructure, mechanical property and corrosion behaviors of three kinds(α, α+β, β) of as-extruded Mg-Li(1, 9 and 15 wt.%)-1 Ca alloys were investigated using optical microscope, X-ray diffraction(XRD), tensile,immersion and electrochemical polarization measurements.In vitro biocompatibility was evaluated by cytotoxicity assays,hemolysis and four coagluation tests. The results indicated that the Mg-1 Li-1 Ca and Mg-15 Li-1 Ca alloys were characterized by α-Mg and β-Li phases besides Mg2 Ca particles, respectively; while the Mg-9 Li-1 Ca by dual(α-Mg+β-Li) phase together with Mg2 Ca phase. The Mg-1 Li-1 Ca alloy had the highest ultimate tensile strength(UTS) and yield strength(YS)and the lowest elongation(EL) to failure(10.1±1.24%) as well.The EL for the Mg-9 Li-1 Ca alloy was the highest(52.2±0.01%).The long-term immersion tests revealed a decrease in corrosion resistance with increasing Li content. The results of cytotoxicity assays clearly showed that the Mg-Li-Ca alloys demonstrated no toxicity to L-929 cells in 10% concentration of extracts. The Mg-1 Li-1 Ca alloy also exhibited an acceptable hemolysis ratio. The results of four coagulation tests designated no sign of thrombogenicity for the Mg-Li-Ca alloys except for the Mg-15 Li-1 Ca alloy.