NiTi superelasticity via atomistic simulations
NiTi superelasticity via atomistic simulations
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DOI：
10.1080/09500839.2015.1123819
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发表时间：
2015-12
影响因子：
1.2
通讯作者：
Piyas Chowdhury;G. Ren;H. Sehitoglu
中科院分区：
文献类型：
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作者：
Piyas Chowdhury;G. Ren;H. Sehitoglu
NiTi形状记忆合金（SMAs）是下一代多功能材料的理想候选材料。这些材料是超弹性的，也就是说，一旦去除机械力，即使在相当大的非弹性变形之后，它们也能完全恢复原来的形状。据报道，超弹性源于原子尺度的晶体转变。然而，很少有计算机模拟出现，阐明了离散晶格水平的转换机制，这是非凡应变恢复能力的基础。在此，我们对镍钛单晶的超弹性行为进行了突破性的分子动力学建模，并揭示了其原子成因。模拟结果表明，变形恢复是由奥氏体晶体向马氏体晶体可逆转变引起的。我们孤立地考察了拉压不对称的机理起源和压力/温度/应变率变化的影响。因此，这项工作为在更复杂的热机械载荷情况下基于中尺度物理的NiTi性能探测提供了一个新的维度。
The NiTi shape memory alloys (SMAs) are promising candidates for the next-generation multifunctional materials. These materials are superelastic i.e. they can fully recover their original shape even after fairly large inelastic deformations once the mechanical forces are removed. The superelasticity reportedly stems from atomic scale crystal transformations. However, very few computer simulations have emerged, elucidating the transformation mechanisms at the discrete lattice level, which underlie the extraordinary strain recoverability. Here, we conduct breakthrough molecular dynamics modelling on the superelastic behaviour of the NiTi single crystals, and unravel the atomistic genesis thereof. The deformation recovery is clearly traced to the reversible transformation between austenite and martensite crystals through simulations. We examine the mechanistic origin of the tension–compression asymmetries and the effects of pressure/temperature/strain rate variation isolatedly. Hence, this work essentially brings a new dimension to probing the NiTi performance based on the mesoscale physics under more complicated thermo-mechanical loading scenarios.