对不同尺寸的镍钛形状记忆合金试样进行了静态压缩试验，结果表明，镍钛形状记忆合金在静态压缩时表现出了明显的尺寸效应：在所研究的高径比范围内，随着高径比的增加，试样在加载阶段具有硬化现象，卸载阶段具有软化现象；母相及应力诱发马氏体相弹性模量都随高径比的增加而增加；相变超弹性曲线包围的面积，即相变滞后宽度也随高径比的增加显著增加；应力诱发马氏体相变初始应力随高径比的增加具有分段性，由此推测存在一临界高径比，在高于和低于临界高径比的两个范围内，相变初始应力都随高径比的增加而降低，在临界高径比处，相变初始应力跳跃很大。
Static compression experiment was conducted to a NiTi shape memory alloy(SMA) with different sizes. The results show that the NiTi SMA exhibits a significant size effect in static compression. It is found that in the range of the ratio of height to diameter used in present study, as the ratio increases, the specimen shows hardening phenomenon in loading stage and softening phenomenon in unloading stage, and elastic modulus of the parent phase and stress-induced martensitie also increases. The area of the hysteresis loops of the alloy increases significantly with the increase of the ratio as well, which indicates that the width of phase transformation hysteresis loop significantly increases. The change of initial stress for stress-induced martensitie transformation is piecewise as the ratio increases, a critical ratio of height to diameter exits, at which the uncontinuous change of the initial stress for the stress-induced martensitic transformation is observed, when the ratio is lower and higher than the critical value the initial stress for the stress-induced martensitie transformation declines with the increase of the ratio.
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