Ti Ni alloys, with their unique shape memory effects and super elastic properties, occupy an indispensable place in the family of metallic biomaterials. In the past years, surface treatment is the main technique to im...Ti Ni alloys, with their unique shape memory effects and super elastic properties, occupy an indispensable place in the family of metallic biomaterials. In the past years, surface treatment is the main technique to improve the bioinert nature of microcrystalline Ti Ni alloys and inhibit on the release of toxic nickel ions to obtain excellent osteogenesis and osseointegration function. In the present study, nanocrystalline Ti49.2Ni50.8 alloy has been fabricated via equal channel angular pressing(ECAP), and the in vitro and in vivo studies revealed that it had enhanced cell viability, adhesion, proliferation, ALP(Alkaline phosphatase)activity and mineralization, and increased periphery thickness of new bone, in comparison to the commercial coarse-grained counterpart. These findings indicate that the reduction of grain size is beneficial to increasing the biocompatibility of Ti49.2Ni50.8 shape memory alloy.展开更多
High-pressure torsion(HPT)processing under a pressure of 6.0 GPa was applied to Ti29.7Ni50.3Hf20(at.%)alloy.Two types of structure were observed after HPT with 3 revolutions:first one is the mixture of amorphous phase...High-pressure torsion(HPT)processing under a pressure of 6.0 GPa was applied to Ti29.7Ni50.3Hf20(at.%)alloy.Two types of structure were observed after HPT with 3 revolutions:first one is the mixture of amorphous phase and retained nanocrystalline;second is the alternating bands of amorphous phase and high defect density crystalline.As a result,post deformation annealing(PDA)at 500-700℃leads to the non-uniform distribution of martensite and parent phase grains.The grains of martensite are twice larger compared to that of parent phase.The nanocrystalline and ultrafine grains form after annealing at 500-600℃and 700℃,respectively.The twinning mechanism does not change with the reduction of martensitic grains up to^35 nm.The relationship between strength and grain size in Ti29.7Ni50.3Hf20 alloy obeys the classical Hall-Petch relationship with a coefficient of 10.80±0.39 GPa nm^1/2.展开更多
In the present work,the biomedical as-cast pure Mg,Mg–1 Ca and Mg–2 Sr alloys were processed with equal channel angular pressing(ECAP)technique to develop ultrafine microstructure within the materials,and their micr...In the present work,the biomedical as-cast pure Mg,Mg–1 Ca and Mg–2 Sr alloys were processed with equal channel angular pressing(ECAP)technique to develop ultrafine microstructure within the materials,and their microstructures,mechanical properties,degradation behavior,cytocompatibility in vitro and biocompatibility in vivo were studied comprehensively.Finer-gained microstructures and improved mechanical properties of these three materials after ECAP were confirmed compared to their as-cast counterparts.Moreover,after ECAP the degradation rate of pure Mg was increased while that of Mg–1 Ca or Mg–2 Sr alloys decreased compared to the ascast counterparts.Additionally,good in vitro cytocompatibility and in vivo biocompatibility of these three materials were revealed by cell cultural tests using osteoblastic MC3 T3-E1 and human mesenchymal stem cells(h MSC)and in vivo animal tests at the lateral epicondyle of SD-rats’femur.This study offers an alternative powerful avenue to achieve good comprehensive properties of magnesium-based biodegradable metals.It might also help to extend the applied range of magnesium-based biodegradable metals in orthopedic field.展开更多
基金supported by the National Key R&D Program of China (No. 2018YFC1106600)National Natural Science Foundation of China (NSFC)+4 种基金the Russian Foundation for Basic Research (RFBR) NSFC-RFBR Cooperative Project (No. 51611130054)the National Natural Science Foundation of China (Nos. 51431002 and 51871004)the National Natural Science Foundation of China (NSFC)the Research Grants Council (RGC) of Hong Kong NSFC-RGC Joint Research Scheme (Grant No. 5161101031)the financial support from Saint Petersburg State University in the framework of Call 3 project (id 26130576)
文摘Ti Ni alloys, with their unique shape memory effects and super elastic properties, occupy an indispensable place in the family of metallic biomaterials. In the past years, surface treatment is the main technique to improve the bioinert nature of microcrystalline Ti Ni alloys and inhibit on the release of toxic nickel ions to obtain excellent osteogenesis and osseointegration function. In the present study, nanocrystalline Ti49.2Ni50.8 alloy has been fabricated via equal channel angular pressing(ECAP), and the in vitro and in vivo studies revealed that it had enhanced cell viability, adhesion, proliferation, ALP(Alkaline phosphatase)activity and mineralization, and increased periphery thickness of new bone, in comparison to the commercial coarse-grained counterpart. These findings indicate that the reduction of grain size is beneficial to increasing the biocompatibility of Ti49.2Ni50.8 shape memory alloy.
基金supported by National Key R&D Program of China[grant number 2017YFE0123500]National Natural Science Foundation of China[grant number 51971072,51671064]+2 种基金the Fundamental Research Funds for the Central University[grant number HEUCFG201836]the support from the RFBR-CNPq-DST research project№19-58-80018the support in part from the Russian Foundation for Basic Research(project No.20-03-00614)。
文摘High-pressure torsion(HPT)processing under a pressure of 6.0 GPa was applied to Ti29.7Ni50.3Hf20(at.%)alloy.Two types of structure were observed after HPT with 3 revolutions:first one is the mixture of amorphous phase and retained nanocrystalline;second is the alternating bands of amorphous phase and high defect density crystalline.As a result,post deformation annealing(PDA)at 500-700℃leads to the non-uniform distribution of martensite and parent phase grains.The grains of martensite are twice larger compared to that of parent phase.The nanocrystalline and ultrafine grains form after annealing at 500-600℃and 700℃,respectively.The twinning mechanism does not change with the reduction of martensitic grains up to^35 nm.The relationship between strength and grain size in Ti29.7Ni50.3Hf20 alloy obeys the classical Hall-Petch relationship with a coefficient of 10.80±0.39 GPa nm^1/2.
基金supported by National Key Research and Development Program of China(No.2018YFC1106600)National Natural Science Foundation of China(Grant No.51871004)+1 种基金NSFC/RGC Joint Research Scheme(Grant No.51661165014)the partial financial support in the framework of the RFBR project 20-58-S52001МНТ_а.
文摘In the present work,the biomedical as-cast pure Mg,Mg–1 Ca and Mg–2 Sr alloys were processed with equal channel angular pressing(ECAP)technique to develop ultrafine microstructure within the materials,and their microstructures,mechanical properties,degradation behavior,cytocompatibility in vitro and biocompatibility in vivo were studied comprehensively.Finer-gained microstructures and improved mechanical properties of these three materials after ECAP were confirmed compared to their as-cast counterparts.Moreover,after ECAP the degradation rate of pure Mg was increased while that of Mg–1 Ca or Mg–2 Sr alloys decreased compared to the ascast counterparts.Additionally,good in vitro cytocompatibility and in vivo biocompatibility of these three materials were revealed by cell cultural tests using osteoblastic MC3 T3-E1 and human mesenchymal stem cells(h MSC)and in vivo animal tests at the lateral epicondyle of SD-rats’femur.This study offers an alternative powerful avenue to achieve good comprehensive properties of magnesium-based biodegradable metals.It might also help to extend the applied range of magnesium-based biodegradable metals in orthopedic field.
