Non-negligible role of gradient porous structure in superelasticity deterioration and improvement of NiTi shape memory alloys  

作　　者：Yintao Zhang Daixiu Wei Yang Chen Lechun Xie Liqiang Wang Lai-Chang Zhang Weijie Lu Guang Chen 

机构地区：[1]State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China [2]National Key Laboratory of Advanced Casting Technologies,MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology,Engineering Research Center of Materials Behavior and Design,Ministry of Education,Nanjing University of Science and Technology,Nanjing 210094,China [3]Hubei Key Laboratory of Advanced Technology for Automotive Components,Wuhan University of Technology,Wuhan 430070,China [4]School of Engineering,Edith Cowan University,270 Joondalup Drive,Joondalup,WA 6027,Australia

出　　处：《Journal of Materials Science & Technology》2024年第19期48-63,共16页材料科学技术（英文版）

基　　金：the financial support of the National Natural Science Foundation under Grant No.52274387;project support by the Shanghai Science and Technology Com-mission(Grant No.20S31900100).

摘　　要：Bone-mimicking gradient porous NiTi shape memory alloys(SMAs)are promising for orthopedic im-plants due to their distinctive superelastic functional properties.However,premature plastic deformation in weak areas such as thinner struts,nodes,and sharp corners severely deteriorates the superelasticity of gradient porous NiTi SMAs.In this work,we prepared gradient porous NiTi SMAs with a porosity of 50%by additive manufacturing(AM)and achieved a remarkable improvement of superelasticity by a simple solution treatment regime.After solution treatment,phase transformation temperatures dropped signif-icantly,the dislocation density decreased,and partial intergranular Ti-rich precipitates were transferred into the grain.Compared to as-built samples,the strain recovery rate of solution-treated samples was nearly doubled at a pre-strain of 6%(up to 90%),and all obtained a stable recoverable strain of more than 4%.The remarkable superelasticity improvement was attributed to lower phase transformation tem-peratures,fewer dislocations,and the synergistic strengthening effect of intragranular multi-scale Ti-Ni precipitates.Notably,the gradient porous structure played a non-negligible role in both superelasticity deterioration and improvement.The microstructure evolution of the solution-treated central strut after constant 10 cycles and the origin of the stable superelastic response of gradient porous NiTi SMAs were revealed.This work provides an accessible strategy for improving the superelastic performance of gra-dient porous NiTi SMAs and proposes a key strategy for achieving such high-performance architectured materials.

关 键 词：Shape memory alloys SUPERELASTICITY Gradient porous structure Solution treatment Stable recoverable strain 

分 类 号：TG14[一般工业技术—材料科学与工程]