Effects of microstructure and composition on constitutive response of high temperature shape memory alloys: Micromechanical modeling using 3-D reconstructions with experimental validation
Effects of microstructure and composition on constitutive response of high temperature shape memory alloys: Micromechanical modeling using 3-D reconstructions with experimental validation
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DOI：
10.1016/j.actamat.2022.117929
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发表时间：
2022-04-23
期刊：
影响因子：
9.4
通讯作者：
Lagoudas, Dimitris C.
中科院分区：
文献类型：
--
作者：
Joy, Jobin K.;Umale, Tejas;Lagoudas, Dimitris C.
NiTiHf合金是一种高温形状记忆合金(SMA)，适用于宽温度范围内的致动应用。在NiTiHf SMA中，时效处理导致形成纳米尺寸的非相变和弹性析出，从而改变了相变行为。对时效合金的实验观察表明，随着析出物的析出，相变应变有增加的趋势，这与人们的直觉相反。为了预测这种微观结构对析出NiTiHf形状记忆合金本构响应的影响，本文建立了一个基于有限元的细观力学建模框架。考虑了两种具有代表性的体积元素：(I)用透射电子显微镜对沉淀进行精确的三维重建，以及(Ii)用较便宜的椭球表示沉淀。模拟了材料的成分变化，并考虑了相变性质对材料成分的影响。利用所建立的模型预测了Ni50合金在不同时效条件下的本构响应。3Ti29.7Hf20和Ni50。3Ti34。7小时15个SMA。模型预测结果与实验测量结果吻合较好，实验和模拟结果均以样本间变化的可信区间给出。本工作首次建立了考虑真实微结构的高温SMA的细观力学模型。(C)2022 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
NiTiHf alloys are high temperature Shape Memory Alloys (SMAs) suitable for actuation applications in a wide range of temperatures. Aging heat treatments in NiTiHf SMAs cause the formation of nano-sized, non-transforming and elastic precipitates, which modify phase transformation behavior. Experimental observations of the aged alloys showed a counterintuitive trend of increasing phase transformation strain with precipitation. In order to predict such microstructure effects on constitutive response of precipitated NiTiHf SMAs, in this work a finite element based micromechanical modeling framework is developed. Two types of representative volume elements are considered: (i) exact 3-D reconstructions of precipitates using transmission electron microscopy, and (ii) less expensive ellipsoidal representation of precipitates. The composition changes in the material are modeled, and their effects are incorporated by considering composition dependency of phase transformation properties in the matrix. The resulting model is used to predict the constitutive responses for different aging conditions in Ni50. 3Ti29. 7Hf20 and Ni50. 3Ti34. 7Hf15 SMAs. The model predictions are in good agreement with the experimental measurements, and experimental and modeling results are presented with confidence intervals from sample-to-sample variations. The present work constitutes the first micromechanical modeling of high temperature SMAs with consideration of real microstructures. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.