Simultaneous enhancement of mechanical and shape memory properties by heat-treatment homogenization of Ti_(2)Ni precipitates in TiNi shape memory alloy fabricated by selective laser melting  

作　　者：H.Z.Lu L.H.Liu C.Yang X.Luo C.H.Song Z.Wang J.Wang Y.D.Su Y.F.Ding L.C.Zhang Y.Y.Li 

机构地区：[1]National Engineering Research Center of Near-net-shape Forming for Metallic Materials,South China University of Technology,Guangzhou 510640,China [2]Musculoskeletal Oncology Department,Sun Yat-Sen University Cancer Center,Guangzhou,Guangdong Province,China [3]Shenyang Aircraft Design and Research Institute,Shenyang 110035,China [4]Guangdong Huayi Plumbing Fittings Industry Co.,Ltd.,Kaiping 529321,China [5]School of Engineering,Edith Cowan University,270 Joondalup Drive,Joondalup,Perth,WA 6027,Australia

出　　处：《Journal of Materials Science & Technology》2022年第6期205-216,共12页材料科学技术（英文版）

基　　金：supported financially by the Key-Area Research and Development Program of Guangdong Province (No. 2020B090923001);the National Natural Science Foundation of China (No. U19A2085);the Key Basic and Applied Research Program of Guangdong Province (No. 2019B030302010);the financial support from the China Postdoctoral Science Foundation (No. 2019M662908);Guangdong Basic and Applied Basic Research Foundation (No.2019A1515110215);the Fundamental Research Funds for the Central Universities (No.2020ZYGXZR030)。

摘　　要：The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(SMAs) fabricated using selective laser melting(SLM) are highly desirable for a wide range of critical applications. In this study, we examined the simultaneous enhancement of mechanical and shape memory properties using heat-treatment homogenization of Ti_(2)Ni precipitates in a Ti_(50.6)Ni_(49.4)SMA fabricated using SLM. Specifically, because of the complete solution treatment, nanoscale spherical Ti_(2)Ni precipitates were homogeneously dispersed throughout the grain interior. Interestingly, the resultant SMA exhibited an ultrahigh tensile strength of 880 ± 13 MPa, a large elongation of 22.4 ± 0.4%, and an excellent shape memory effect, with a recovery rate of > 98% and ultrahigh recoverable strain of 5.32% after ten loading–unloading cycles. These simultaneously enhanced properties are considerably superior than those of most previously reported Ti Ni SMAs fabricated using additive manufacturing. Fundamentally, the enhancement in tensile strength is ascribed to precipitation strengthening and work hardening, and the large plasticity is mainly attributed to the homogeneous nanoscale globular Ti_(2)Ni precipitates, which effectively impeded the rapid propagation of microcracks. Furthermore, the enhanced shape memory properties are derived from the suppression of dislocation movement and formation of retained stabilized martensite by the presence of high-density dislocations, nanoscale Ti_(2)Ni precipitates, and abundant interfaces. The obtained results provide insight into the enhancement of the two types of properties in Ti Ni SMAs and will accelerate the wider application of SMAs.

关 键 词：Shape memory alloy Selective laser melting Heat treatment Mechanical properties Shape memory properties 

分 类 号：TG139.6[一般工业技术—材料科学与工程]