Mo and Ta addition in NbTiZr medium entropy alloy to overcome tensile yield strength-ductility trade-off  

作　　者：Muhammad Akmal Hyun Woo Seong Ho Jin Ryu 

机构地区：[1]Department of Materials Science and Engineering,KAIST,Daejeon,Yuseong-gu 34141,South Korea [2]Department of Nuclear and Quantum Engineering,KAIST,Daejeon,Yuseong-gu 34141,South Korea

出　　处：《Journal of Materials Science & Technology》2022年第14期176-185,共10页材料科学技术（英文版）

基　　金：supported by the National Research Foundation of Korea(NRF-2020R1A5A6017701,NRF-2121R1A2C2014025)。

摘　　要：In this study,single-phase NbTiZr and NbTiZr(MoTa)_(0.1) medium-entropy alloys(MEAs)were investigated for their use in biomedical implants.The alloys were prepared by arc melting,and were then cold-rolled,annealed,and characterized in terms of phase analysis,mechanical properties,fractography,and wear resistance.Both alloys showed a single body-centered cubic phase with superior mechanical,and tribological properties compared to commercially available biomedical alloys.Mo and Ta-containing MEAs showed higher tensile yield strength(1060±18 MPa)and higher tensile ductility(~20%),thus overcoming the strength-ductility trade-off with no signs of transformation-induced plasticity,twinning,or precipitation.The generalized stacking fault energy(GSFE)calculations on the{112}<111>slip system by the first-principles calculations based on density functional theory showed that the addition of less than0.2 molar fraction of Mo and Ta lowers the GSFE curves.This behavior posits the increase in ductility of the alloy by facilitating slips although strength is also increased by solid solution strengthening.The wear resistance of both alloys against hardened steel surfaces was superior to that of commercial biomedical alloys.Thus,we concluded that NbTiZr(MoTa)_(0.1)MEA with good tensile ductility is a potential candidate for biomedical implants.

关 键 词：Medium-entropy alloys WEAR-RESISTANT Biomedical implants Solid solution hardening Staking fault energy 

分 类 号：TG139[一般工业技术—材料科学与工程]