Texture and grain neighborhood effects on Ni–Ti shape memory alloy performance
Texture and grain neighborhood effects on Ni–Ti shape memory alloy performance
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DOI：
10.1088/0965-0393/22/7/075002
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发表时间：
2014-09
影响因子：
1.8
通讯作者：
H. Paranjape;P. Anderson
中科院分区：
文献类型：
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作者：
H. Paranjape;P. Anderson
这项工作演示了如何统计的伪弹性性能的单个晶粒的影响，局部晶粒附近的多晶形状记忆合金（SMA）。这是使用校准到均匀化Ti-50.9 at% Ni SMA的微观结构有限元（FE）模型实现的。结果表明，在随机织构的多晶体中，晶粒水平轴向相变应变pT的三倍变化，并且如果塑性预变形，平均pT降低约20-30%。一个关键的结果是一个性能函数来预测的颗粒的pT，基于晶粒及其邻居的取向。确定了提高多晶SMA性能的两个关键策略。第一个是最大限度地减少高性能和低性能晶粒之间的晶界数量：板材和竹子几何形状可以实现这一点。第二种是采用这些晶粒之间的高对称性取向关系。结果借鉴了最近的实验研究晶粒级性能，并提供了一个理论框架来解释未来的衍射层析成像研究。
This work demonstrates how the statistical pseudoelastic performance of individual grains is affected by the local grain neighborhood in polycrystalline shape memory alloys (SMAs). This is achieved using a microstructural finite element (FE) model calibrated to homogenized Ti-50.9 at% Ni SMA. The results show a three-fold variation in the grain level axial transformation strain pT in randomly textured polycrystals, and a ∼20–30% reduction in average pT if plastically predeformed. A key outcome is a performance function to predict pT of a grain, based on the orientations of the grain and its neighbors. Two key strategies to improve polycrystalline SMA performance are identified. The first is to minimize the number of grain boundaries between high-and low-performing grains: plate and bamboo geometries achieve this. The second is to employ high-symmetry orientation relationships between these grains. The results draw on recent experimental studies of grain level performance and provide a theoretical framework to interpret future diffraction tomography studies.