The evolution of deformation twinning microstructures in random face-centered cubic solid solutions
The evolution of deformation twinning microstructures in random face-centered cubic solid solutions
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DOI：
10.1063/5.0135538
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发表时间：
2023-02
影响因子：
3.2
通讯作者：
Ritesh Jagatramka;Junaid Ahmed;M. Daly
中科院分区：
文献类型：
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作者：
Ritesh Jagatramka;Junaid Ahmed;M. Daly
面心立方(FCC)固溶体中不同的原子排列使其能谱发生原子尺度的涨落，从而影响位错介导的形变机制的运行。这些影响在集中式系统中尤其明显，这是社会相当感兴趣的。在这里，我们研究了平面断层能的局部涨落对随机排列的面心立方固溶体中形变孪生微结构演化的影响。我们的方法利用动力学蒙特卡罗(KMC)方法为形变孪晶形核和形变孪晶增厚两个过程之间的竞争提供了动力学加权预测。支持每个过程的动能垒来自平面断层能量的统计，这些能量是用分子静力学方法进行局部采样的。KMC结果表明，相对于均匀参照物，固溶体的断层数密度增加，这是由平面断层能量的涨落所驱动的。基于KMC关系，导出了一个有效的势垒模型，用于预测平面断层能量起伏下形变孪晶形核和增厚过程之间的竞争。这个模型的一个关键结果是测量了长度-尺度，在这个尺度上，平面断层能量的局部涨落的影响减小，以成核/增厚为主的行为收敛到整体预测。更广泛地说，这项研究中开发的工具能够检查化学和长度尺度对面心立方固溶体中变形孪生机制演变的影响。
The varied atomic arrangements in face-centered cubic (FCC) solid solutions introduce atomic-scale fluctuations to their energy landscapes that influence the operation of dislocation-mediated deformation mechanisms. These effects are particularly pronounced in concentrated systems, which are of considerable interest to the community. Here, we examine the effect of local fluctuations in planar fault energies on the evolution of deformation twinning microstructures in randomly arranged FCC solid solutions. Our approach leverages the kinetic Monte Carlo (kMC) method to provide kinetically weighted predictions for competition between two processes: deformation twin nucleation and deformation twin thickening. The kinetic barriers underpinning each process are drawn from the statistics of planar fault energies, which are locally sampled using molecular statics methods. kMC results show an increase in the fault number densities of solid solutions relative to a homogenized reference, which is found to be driven by the fluctuations in planar fault energies. Based on kMC relations, an effective barrier model is derived to predict the competition between deformation twinning nucleation and thickening processes under a fluctuating planar fault energy landscape. A key result from this model is a measurement of the length-scale over which the influence of local fluctuations in planar fault energies diminish and nucleation/thickening-dominated behaviors converge to bulk predictions. More broadly, the tools developed in this study enable examination of the influence of chemistry and length-scale on the evolution of deformation twinning mechanisms in FCC solid solutions.