Effect of grain size on the microstructure and mechanical anisotropy of stress-induced martensitic NiTi alloys
Effect of grain size on the microstructure and mechanical anisotropy of stress-induced martensitic NiTi alloys
复制标题
晶粒尺寸对应力诱发马氏体NiTi合金显微组织和力学各向异性的影响
DOI：
10.1016/j.msea.2022.143497
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发表时间：
2022-06
期刊：
影响因子：
--
通讯作者：
Xiaobin Shi
中科院分区：
文献类型：
--
作者：
Wang Tang;Qihang Shen;Xudong Yao;Weihuo Li;Jiang Jiang;Zhixin Ba;Yongtao Li;Xiaobin Shi
应力诱发马氏体常呈择优取向，这导致了NiTi合金的力学各向异性。本文研究了晶粒度对应力诱发马氏体态NiTi显微组织和力学各向异性的影响。纳米晶NiTi具有单晶和无孪晶的纳米晶，超细晶NiTi具有(111)m型І、(2‾01)形变孪晶、(100)形变孪晶和(001)m复合孪晶。显微组织的差异表明，纳米晶和超细晶合金在压痕载荷下具有不同的织构，晶粒发生了重新取向，合金发生了塑性变形。在较低的压痕载荷下，应力诱导的纳米晶NiTi表现出比超细晶NiTi更强的弹性模量各向异性，而应力诱导的超细晶马氏体NiTi表现出更强的硬度各向异性。
Stress-induced martensite always exhibits an oriented microstructure, which leads to mechanical anisotropy in NiTi alloys. In this study, the effects of grain size on the microstructure and mechanical anisotropy of stress-induced-martensitic NiTi were investigated. Nanocrystalline NiTi exhibited single-variant and twin-free nanograins; ultrafine-grained NiTi exhibited (111) m type І, ( 2 ‾ 01 ) deformation twins, (100) deformation twins and (001) m compound twins. Microstructural differences suggest that the nanocrystalline and ultrafine-grained alloys had different textures, grains were reoriented, and alloy deformed plastically upon indentation loading. Stress-induced nanocrystalline martensitic NiTi exhibited considerably stronger elastic-modulus anisotropy than ultrafine-grained NiTi when a lower indentation load was applied, whereas stress-induced ultrafine-grained martensitic NiTi exhibited stronger hardness anisotropy.