Effect of grain size on stress induced martensitic transformations in a Cu–Al–Be polycrystalline shape-memory alloy. Pseudoelastic cycling effects and microstructural modifications
Effect of grain size on stress induced martensitic transformations in a Cu–Al–Be polycrystalline shape-memory alloy. Pseudoelastic cycling effects and microstructural modifications
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DOI：
10.1016/j.msea.2014.05.018
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发表时间：
2014-07
期刊：
影响因子：
6.4
通讯作者：
M. Sade;F. C. Bubani;F. Lovey;V. Torra
中科院分区：
文献类型：
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作者：
M. Sade;F. C. Bubani;F. Lovey;V. Torra
晶粒尺寸对形状记忆合金的伪弹性性能有很大的影响。不同的晶粒尺寸和几个相关的现象进行了研究。这涉及到相变和再相变应力对晶粒尺寸和相变材料量的依赖性。观察到循环时相变应力的显著下降，直到达到渐近行为。这与缺陷（位错和位错阵列）和马氏体微片的产生有关，这些缺陷是由于马氏体相变引起的形状变化而允许晶粒适应所必需的缺陷。渐近滞后与一旦产生必要的缺陷时晶粒相互适应的内部功有关。随着晶粒尺寸的减小，渐近滞后线性增大。一个简单的模型表明，斜率与（d/e）比有关，其中d是平均晶粒尺寸，d是试样的宽度。这种效应是由于自由表面的存在而产生的，自由表面释放了塑性功以容纳颗粒。
Grain size has a strong effect on the pseudoelastic properties of shape-memory alloys. Different grain sizes and several related phenomena are studied. This involves the dependence of the transformation and retransformation stresses on grain size and on the amount of transformed material. A pronounced drop of transformation stresses on cycling is observed, until an asymptotic behavior is reached. This is related to the creation of defects (dislocations and dislocation arrays) and microplates of martensite, which are the defects necessary to allow the grains to accommodate due to the shape change imposed by the martensitic transformation. The asymptotic hysteresis is related to the internal work for the grains to accommodate each other once the necessary defects were created. The asymptotic hysteresis increases linearly as the grain size decreases. A simple model shows that the slope is related to the (d/e) ratio, wheredis the average grain size andeis the width of the specimen. This effect arises from the presence of the free surfaces that release the plastic work for grain accommodation.