Stacking fault based analysis of shear mechanisms at interfaces in lamellar TiAl alloys
Stacking fault based analysis of shear mechanisms at interfaces in lamellar TiAl alloys
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DOI：
10.1016/j.actamat.2015.11.047
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发表时间：
2016-03-01
期刊：
影响因子：
9.4
通讯作者：
Janisch, R.
中科院分区：
文献类型：
--
作者：
Kanani, M.;Hartmaier, A.;Janisch, R.
层状TiAl合金中的界面对组织的强度和变形性能有很大影响。人们普遍认为，可以使用它们的数量和间距来调整这些属性。然而，本文给出的层状TiAl合金中伽马/伽马界面滑动的分子动力学模拟结果表明，必须在介观模型中考虑重要的因素，即不同界面类型的顺序以及面内方向相对于加载轴的取向。双晶剪切模拟表明不同界面的变形行为存在显著差异，各界面剪切强度的面内各向异性明显，双晶剪切模拟得到的临界应力与单晶孪晶形核和运动的临界应力具有相同的数量级，表明这两种机制是相互竞争的。共观察到四种不同的变形机制，即界面迁移、孪晶形核和迁移、位错形核和刚性晶界滑动。基于多层广义层错能分析，可以理解它们的发生。这种物理性能、几何形状和变形机制之间的联系可以为未来合金的发展提供指导。(C)2016年，由Elsevier Ltd代表Acta Materialia Inc.出版。
The interfaces in lamellar TiAl alloys have a strong influence on the strength and deformability of the microstructure. It is widely accepted that their number and spacing can be used to tune these properties. However, the results of molecular dynamics simulations of sliding at gamma/gamma interfaces in lamellar TiAl alloys presented here suggest that important factors, namely the sequence of different interface types as well as the orientation of in-plane directions with respect to the loading axis, have to be included into mesoscale models. Simulations of bicrystal shear show significant differences in the deformation behavior of the different interfaces, as well as pronounced in-plane anisotropy of the shear strength of the individual interfaces.The critical stresses derived from bicrystal shear simulations are of the same order of magnitude as the one for nucleation and motion of twins in a gamma-single crystal, showing that these mechanisms are competitive. In total four different deformation mechanisms, interface migration, twin nucleation and migration, dislocation nucleation, and rigid grain boundary sliding are observed. Their occurrence can be understood based on a multilayer generalized stacking fault energy analysis. This link between physical properties, geometry and deformation mechanism can provide guidelines for future alloy development. (C) 2016 Published by Elsevier Ltd on behalf of Acta Materialia Inc.