Shape-memory transformations of NiTi: minimum-energy pathways between austenite, martensites, and kinetically limited intermediate states.
Shape-memory transformations of NiTi: minimum-energy pathways between austenite, martensites, and kinetically limited intermediate states.
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NiTi 的形状记忆转变：奥氏体、马氏体和动力学限制中间态之间的最小能量路径。
DOI：
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发表时间：
2014
影响因子：
8.6
通讯作者：
Duane D. Johnson
中科院分区：
文献类型：
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作者：
N. Zarkevich;Duane D. Johnson
NiTi是最常用的形状记忆合金;尽管如此，仍然缺乏对相关结构和过渡（包括其势垒）的了解。使用通过密度泛函理论实现的广义固态轻推弹性带方法，我们详细描述了NiTi中与形状记忆相关的结构转变：体心斜方晶系（BCO）基态和新发现的稳定奥氏体之间的那些（“玻璃状”B2-样）结构，包括能垒（滞后）和中间结构（观察为动力学限制的R相），以及马氏体变体（bco取向）之间。所得结果与已有的实验结果吻合较好。我们将奥氏体的结果与通常假设的但不稳定的B2的结果进行对比。这些高温和低温结构和结构转变提供了非常需要的原子尺度的细节负责NiTi形状记忆效应的转变。
NiTi is the most used shape-memory alloy; nonetheless, a lack of understanding remains regarding the associated structures and transitions, including their barriers. Using a generalized solid-state nudged elastic band method implemented via density-functional theory, we detail the structural transformations in NiTi relevant to shape memory: those between a body-centered orthorhombic (bco) ground state and a newly identified stable austenite ("glassy" B2-like) structure, including energy barriers (hysteresis) and intermediate structures (observed as a kinetically limited R phase), and between martensite variants (bco orientations). All results are in good agreement with available experiment. We contrast the austenite results to those from the often-assumed, but unstable B2. These high- and low-temperature structures and structural transformations provide much needed atomic-scale detail for transitions responsible for NiTi shape-memory effects.