Microstructures evolution and phase transformation behaviors of Ni-rich TiNi shape memory alloys after equal channel angular extrusion
Microstructures evolution and phase transformation behaviors of Ni-rich TiNi shape memory alloys after equal channel angular extrusion
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DOI：
10.1016/j.jallcom.2010.11.189
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发表时间：
2011-02
影响因子：
6.2
通讯作者：
Xiaoning Zhang;Jie Song;Chenglong Huang;B. Xia;Bing Chen;Xiaogang Sun;C. Xie
中科院分区：
文献类型：
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作者：
Xiaoning Zhang;Jie Song;Chenglong Huang;B. Xia;Bing Chen;Xiaogang Sun;C. Xie
采用Bc路径对富Ni TiNi形状记忆合金在773 K下进行等通道转角挤压（ECAE），研究了ECAE工艺对合金组织演变和相变行为的影响。试样初始为60-80μm的等轴粗晶沿ECAE剪切力方向被沿着拉长，经过8道次ECAE后细化至300- 400 nm。在较大的温度范围内，用ECAE工艺模拟了富Ni TiNi形状记忆合金的R相变。在ECAE前1-3次处理中，马氏体相变峰温（Mp）有所下降，但随着ECAE处理次数的增加，Mp下降幅度逐渐增大。ECAE处理后位错密度高的区域出现了Ti 3 Ni 4相。并对显微组织演变和相变变化的原因进行了讨论。
Ni-rich TiNi shape memory alloys were subjected to the effect of equal channel angular extrusion (ECAE) processes at 773K by Bc path. The effects of ECAE processes on microstructures evolution and phase transformation behaviors were investigated. The initial 60–80μm equiaxed coarse grains of samples were elongated along the shearing force direction of ECAE and refined to 300–400nm after eight passes ECAE. The R phase transformation of Ni-rich TiNi shape memory alloys was stimulated by ECAE processes within a larger temperature range. The martensite transformation peak temperature (Mp) dropped in previous 1–3 ECAE treatments, but the dropped Mp increased gradually with the increase of ECAE processes. Ti3Ni4phase was observed in the regions with high density of dislocations after ECAE treatment. Reasons for microstructures evolution and phase transformation changes were also discussed.