Ti-Nb alloys have great potential in biomedical applications as bone-implant materials due to their low elastic modulus,superelasticity,high corrosion resistance,and good biocompatibility.However,the low yield strengt...Ti-Nb alloys have great potential in biomedical applications as bone-implant materials due to their low elastic modulus,superelasticity,high corrosion resistance,and good biocompatibility.However,the low yield strength and poor superelasticity of Ti-Nb alloys restrict their practical clinical applications.Here,we report the mechanical properties and superelasticity,corrosion behavior,and biocompatibility of a Ti-26 at.%Nb-1.2 vol.%TiC(Ti-26Nb-1.2TiC)shape memory composite(SMC)prepared by vacuum arc melting and hot rolling.The yield strength,critical stress for inducing martensitic transformation,and elongation of the Ti-26Nb-1.2TiC SMC and a Ti-26Nb alloy were 460 and 337 MPa,251 and 115 MPa,and 27.2%and 24.1%,respectively.The recovery rate of the SMC under 4%pre-strain reached 91.4%,which was 1.2 times that of the Ti-26Nb.Electrochemical tests in Hanks’solution revealed that the corrosion current density,passive current density,and corrosion rate of the SMC were lower than those of the Ti-26Nb.Both the Ti-26Nb alloy and Ti-26Nb-1.2TiC SMC showed good cell viability with grade 0 cytotoxicity in relation to MG-63 osteosarcoma cells.展开更多
In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed b...In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed by hot-rolling, annealing, and quenching. The microstructure and mechanical properties were characterized by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), micro-region X-ray diffractometry(MRXRD), nanoindentation, and in-situ scanning electron microscopy tensile testing. The results show that the Ti-18 Nb consists of Ti-enriched, diffusion and Nb-enriched zones, and the sharp Nb gradient across different zones leads to inhomogeneous distribution of phase and mechanical properties. A remarkable finding is that the diffusion zones not only enable the cooperative deformation between the brittle Ti-enriched zones and the ductile Nb-enriched zones but also act as the crack-arresters to prevent the local cracks in the Ti-enriched zones from further propagating across the composite.展开更多
Titanium and its alloys have been extensively used as implant materials owing to their high specific strength, good biocompatibility and excellent corrosion resistance. Oxide nanotubular array layer can be formed on T...Titanium and its alloys have been extensively used as implant materials owing to their high specific strength, good biocompatibility and excellent corrosion resistance. Oxide nanotubular array layer can be formed on Ti alloy surface by electrochemical anodization treatment. In this work, the morphology of nanotubes formed on Ti-Nb alloys（Nb content of 5 wt%, 10 wt%, 20 wt%, 30 wt% and40 wt%） was investigated using an electrolyte containing ethylene glycol and NH_4 F. Oxide layers consisting of highly ordered nanotubes with a range of diameters（approximately40-55 nm for the inner diameter and 100-120 nm for the outer diameter） and lengths（approximately 10-20 lm） can be formed on alloys in the Ti-x Nb system, independent on the Nb content. The nanotubes formed on the Ti-Nb alloy surface were transformed from the anatase to rutile structure of titanium oxide. The oxide nanotubular surface is highly hydrophilic compared with the intact Ti Nb foil. The surface wettability varies with the nanotube diameter. As the nanotube diameter increases while the nanotube layer thickness remains constant, the capillary wetting of the nanotube surface decreases and the surface becomes less hydrophilic.Annealing changes the nanotubular surface wettability further and establishes less hydrophilic surface conditions due to the removal of hydroxyl groups and residue fluoridecontaining species. It is believed that the surface wettability is changed due to the decreasing content of hydroxyl groups in ambient atmosphere. This work can provide guidelines for improving structural and environmental conditions responsible for changing surface wettability of Ti Nb surfaces for biomedical applications.展开更多
The microstructure and properties of a series of binary Ti-Nb alloys for dental prostheses with niobium contents ranging from 5% to 20% were investigated. The experimental results indicate that the crystal structure a...The microstructure and properties of a series of binary Ti-Nb alloys for dental prostheses with niobium contents ranging from 5% to 20% were investigated. The experimental results indicate that the crystal structure and morphology of Ti-Nb alloys are sensitive to their niobium contents. When Nb content is 5%, the acicular α crystal grain is observed. When Nb content is 10%, the coarse equiaxed crystal grain and the fine, acicular α crystal grain are observed. When Nb content is 15%, only the α equiaxed crystal grain is observed. When the alloy contains 20%Nb, the equiaxed and dendritic α crystal grain are observed. For Ti-Nb alloys, the increase of Nb content modifies the microstructure of Ti-Nb alloys significantly and decreases their compression elastic modulus, in which Ti-20Nb alloy shows the largest compression strength and Ti-5Nb alloy shows the best plasticity. The dry wear resistance of Ti-Nb alloys against Gr15 ball was investigated on CJS111A ball-disk wear instrument. For Ti-Nb alloys, Ti-10Nb alloy shows a smallest steady friction coefficient, Ti-5Nb alloy shows the smallest wear depth and best wear resistance, and Ti-15Nb alloy shows the largest wear depth and worst wear resistance. The phenomenon of furrow cut happens and furrows form during wear tests.展开更多
To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the...To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti Nb-bearing Fe concentrate/coal composite pel- let was reduced at temperatures greater than 1100℃. The addition of CaCO3 improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100~C were analyzed by X-ray diffraction and scanning electron microsco- py-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100℃ for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet.展开更多
Porous Ti35Nb alloy with a porosity of 66% was made by a powder metallurgical method, and then it was treated by a standard treatment for activating the surface of Ti implant materials involving alkali and heat treatm...Porous Ti35Nb alloy with a porosity of 66% was made by a powder metallurgical method, and then it was treated by a standard treatment for activating the surface of Ti implant materials involving alkali and heat treatment. The alkali and heat treatment causes damages of the struts of the porous Ti35Nb in the form of reaction products layer, grain-pullout and cracks. Consequently, it leads to a significant degradation of the strength of the porous alloy. The effect of the alkali and heat treatment on the strength of the porous alloy was discussed.展开更多
A metallurgical model concerning the co-effect of the Nb solute drag and the complex carbonitride precipitates pinning is proposed to predict the recrystallization austenite grain growth of low carbon Nb-containing mi...A metallurgical model concerning the co-effect of the Nb solute drag and the complex carbonitride precipitates pinning is proposed to predict the recrystallization austenite grain growth of low carbon Nb-containing microalloyed steels.The analysis,both predicted and experimental,reveals the precipitate pinning plays a dominate role in suppressing the austenite grain growth with less Nb solute drag effect in high temperature region whereas the Nb solute drag predominates in relatively low temperature region.A factor p is suggested to assess the effectiveness of drag and pinning.The pinning and the drag are more effective in restraining grain growth as p】0 and p【0,respectively.A low carbon Nb microalloyed steel and a kind of Ti-modified low carbon Nb steel by Ti substituting for part of Nb are employed to validate the modeling results.The theoretical calculations show a good agreement with experimental results.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.51971190 and 11872053)support for this research by the Australian Research Council (ARC)through the Discovery Project (No.DP210101862)Future Fellowship (No.FT160100252).
文摘Ti-Nb alloys have great potential in biomedical applications as bone-implant materials due to their low elastic modulus,superelasticity,high corrosion resistance,and good biocompatibility.However,the low yield strength and poor superelasticity of Ti-Nb alloys restrict their practical clinical applications.Here,we report the mechanical properties and superelasticity,corrosion behavior,and biocompatibility of a Ti-26 at.%Nb-1.2 vol.%TiC(Ti-26Nb-1.2TiC)shape memory composite(SMC)prepared by vacuum arc melting and hot rolling.The yield strength,critical stress for inducing martensitic transformation,and elongation of the Ti-26Nb-1.2TiC SMC and a Ti-26Nb alloy were 460 and 337 MPa,251 and 115 MPa,and 27.2%and 24.1%,respectively.The recovery rate of the SMC under 4%pre-strain reached 91.4%,which was 1.2 times that of the Ti-26Nb.Electrochemical tests in Hanks’solution revealed that the corrosion current density,passive current density,and corrosion rate of the SMC were lower than those of the Ti-26Nb.Both the Ti-26Nb alloy and Ti-26Nb-1.2TiC SMC showed good cell viability with grade 0 cytotoxicity in relation to MG-63 osteosarcoma cells.
基金Project(51625404)supported by the National Natural Science Foundation for Distinguished Young Scholar of ChinaProjects(51604104,51504295)supported by the National Natural Science Foundation of China
文摘In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed by hot-rolling, annealing, and quenching. The microstructure and mechanical properties were characterized by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), micro-region X-ray diffractometry(MRXRD), nanoindentation, and in-situ scanning electron microscopy tensile testing. The results show that the Ti-18 Nb consists of Ti-enriched, diffusion and Nb-enriched zones, and the sharp Nb gradient across different zones leads to inhomogeneous distribution of phase and mechanical properties. A remarkable finding is that the diffusion zones not only enable the cooperative deformation between the brittle Ti-enriched zones and the ductile Nb-enriched zones but also act as the crack-arresters to prevent the local cracks in the Ti-enriched zones from further propagating across the composite.
基金financially supported by the Beijing Higher Education Young Elite Teacher Project(No.YETP0419)the National Natural Science Foundation of China(No.51204015)+1 种基金the project from Ministry of Science and Technology(No.2014BAI11B04)the project from the State Key Laboratory of Advanced Metals and Materials,University of Science and Technology Beijing(No.2012Z-10)
文摘Titanium and its alloys have been extensively used as implant materials owing to their high specific strength, good biocompatibility and excellent corrosion resistance. Oxide nanotubular array layer can be formed on Ti alloy surface by electrochemical anodization treatment. In this work, the morphology of nanotubes formed on Ti-Nb alloys（Nb content of 5 wt%, 10 wt%, 20 wt%, 30 wt% and40 wt%） was investigated using an electrolyte containing ethylene glycol and NH_4 F. Oxide layers consisting of highly ordered nanotubes with a range of diameters（approximately40-55 nm for the inner diameter and 100-120 nm for the outer diameter） and lengths（approximately 10-20 lm） can be formed on alloys in the Ti-x Nb system, independent on the Nb content. The nanotubes formed on the Ti-Nb alloy surface were transformed from the anatase to rutile structure of titanium oxide. The oxide nanotubular surface is highly hydrophilic compared with the intact Ti Nb foil. The surface wettability varies with the nanotube diameter. As the nanotube diameter increases while the nanotube layer thickness remains constant, the capillary wetting of the nanotube surface decreases and the surface becomes less hydrophilic.Annealing changes the nanotubular surface wettability further and establishes less hydrophilic surface conditions due to the removal of hydroxyl groups and residue fluoridecontaining species. It is believed that the surface wettability is changed due to the decreasing content of hydroxyl groups in ambient atmosphere. This work can provide guidelines for improving structural and environmental conditions responsible for changing surface wettability of Ti Nb surfaces for biomedical applications.
基金Project(20080440850) supported by China Postdoctoral Science FoundationProject(ZJY0605-02) supported by the Natural Science Foundation of Heilongjiang Province, China
文摘The microstructure and properties of a series of binary Ti-Nb alloys for dental prostheses with niobium contents ranging from 5% to 20% were investigated. The experimental results indicate that the crystal structure and morphology of Ti-Nb alloys are sensitive to their niobium contents. When Nb content is 5%, the acicular α crystal grain is observed. When Nb content is 10%, the coarse equiaxed crystal grain and the fine, acicular α crystal grain are observed. When Nb content is 15%, only the α equiaxed crystal grain is observed. When the alloy contains 20%Nb, the equiaxed and dendritic α crystal grain are observed. For Ti-Nb alloys, the increase of Nb content modifies the microstructure of Ti-Nb alloys significantly and decreases their compression elastic modulus, in which Ti-20Nb alloy shows the largest compression strength and Ti-5Nb alloy shows the best plasticity. The dry wear resistance of Ti-Nb alloys against Gr15 ball was investigated on CJS111A ball-disk wear instrument. For Ti-Nb alloys, Ti-10Nb alloy shows a smallest steady friction coefficient, Ti-5Nb alloy shows the smallest wear depth and best wear resistance, and Ti-15Nb alloy shows the largest wear depth and worst wear resistance. The phenomenon of furrow cut happens and furrows form during wear tests.
基金financial support of the Fundamental Research Funds for the Central Universities (FRF-TP-16-019A1)the State Key Laboratory of Advanced Metallurgy (41617007), University of Science and Technology Beijing
文摘To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti Nb-bearing Fe concentrate/coal composite pel- let was reduced at temperatures greater than 1100℃. The addition of CaCO3 improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100~C were analyzed by X-ray diffraction and scanning electron microsco- py-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100℃ for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet.
基金Project(2010FJ3132)supported by the Scientific and Technological Project of Hunan Science and Technology Commission,ChinaProject(09A089)supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘Porous Ti35Nb alloy with a porosity of 66% was made by a powder metallurgical method, and then it was treated by a standard treatment for activating the surface of Ti implant materials involving alkali and heat treatment. The alkali and heat treatment causes damages of the struts of the porous Ti35Nb in the form of reaction products layer, grain-pullout and cracks. Consequently, it leads to a significant degradation of the strength of the porous alloy. The effect of the alkali and heat treatment on the strength of the porous alloy was discussed.
文摘A metallurgical model concerning the co-effect of the Nb solute drag and the complex carbonitride precipitates pinning is proposed to predict the recrystallization austenite grain growth of low carbon Nb-containing microalloyed steels.The analysis,both predicted and experimental,reveals the precipitate pinning plays a dominate role in suppressing the austenite grain growth with less Nb solute drag effect in high temperature region whereas the Nb solute drag predominates in relatively low temperature region.A factor p is suggested to assess the effectiveness of drag and pinning.The pinning and the drag are more effective in restraining grain growth as p】0 and p【0,respectively.A low carbon Nb microalloyed steel and a kind of Ti-modified low carbon Nb steel by Ti substituting for part of Nb are employed to validate the modeling results.The theoretical calculations show a good agreement with experimental results.
