钛镍合金
材料科学
退火(玻璃)
形状记忆合金
晶体孪晶
无扩散变换
变形(气象学)
无定形固体
纳米晶材料
马氏体
复合材料
结晶
R相
冶金
合金
微观结构
结晶学
热力学
化学
纳米技术
物理
作者
Dong Sun,Shuyong Jiang,Yanqiu Zhang,Bingyao Yan,Junbo Yu
标识
DOI:10.1016/j.jallcom.2021.159550
摘要
Abstract Equiatomic NiTi shape memory alloy (SMA) undergoing solution treatment, which contains { 1 ¯ 11 } type Ⅰ twin and 〈 011 〉 type Ⅱ twin, suffers from severe plastic deformation (SPD) using local canning compression, where nanocrystalline grains, amorphous phase, deformation twin and detwinning can be observed. SPD-processed NiTi alloy is subjected to subsequent annealing for 2 h at 300, 450 and 600 °C, respectively. 〈 011 〉 type Ⅱ twin still arises in NiTi sample annealed at 300 °C and it is attributed to incomplete detwinning of 〈 011 〉 type Ⅱ twin in the solution-treated NiTi sample. (001) compound twin appears in NiTi sample undergoing annealing at 450 °C and it results from the retained deformation twin due to plastic deformation of solution-treated NiTi sample. However, both (001) compound twin and 〈 011 〉 type Ⅱ twin occur in NiTi specimen annealed at 600 °C and they are generated in the new grains as a result of crystallization. The existence of the twins substantially influences phase transformation of NiTi SMA. Following annealing at 300 and 450 °C, NiTi SMA exhibits one-stage phase transformation during heating and cooling where the corresponding martensitic transformations of the involved NiTi samples are related closely to the retained twins or the retained coarse grains resulting from SPD. NiTi sample annealed at 600 °C exhibits two-stage transformation of B2-R-B19' on cooling, whereas it presents one-stage transformation from B19' to B2 phase on heating, where the corresponding martensitic transformation of the involved NiTi sample is completely dependent on the occurrence of the twins in the new crystallized grains.
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