Deformation twins in nanocrystalline body-centered cubic Mo as predicted by molecular dynamics simulations
Deformation twins in nanocrystalline body-centered cubic Mo as predicted by molecular dynamics simulations
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DOI：
10.1016/j.actamat.2012.08.029
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发表时间：
2012-10
期刊：
影响因子：
9.4
通讯作者：
Yongfeng Zhang;P. Millett;M. Tonks;S. B. Biner
中科院分区：
文献类型：
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作者：
Yongfeng Zhang;P. Millett;M. Tonks;S. B. Biner
本文通过分子动力学模拟研究了体心立方Mo纳米晶中的变形孪晶，包括成核和生长机制及其对延性的影响。采用三种不同取向的柱状晶粒模型模拟了纳米晶Mo的变形过程。所确定的变形机制，包括位错滑移、晶界介导的塑性、变形孪晶和马氏体相变，与先前的研究一致。在< 110 >的柱状晶粒中，变形以孪晶为主，孪晶主要从晶界处连续析出成核，并在晶粒内部逐渐增厚成核。当孪晶被晶界阻滞时，孪晶可能通过激活相容孪晶/滑移系统而在晶界上产生连续的塑性应变，或者在邻近晶粒中没有相容孪晶/滑移系统的情况下导致晶间破坏。在同一晶粒中可以激活多个孪晶系统，它们之间的竞争有利于那些能够在晶界上产生连续变形的孪晶系统。
This work studies deformation twins in nanocrystalline body-centered cubic Mo, including the nucleation and growth mechanisms as well as their effects on ductility, through molecular dynamics simulations. The deformation processes of nanocrystalline Mo are simulated using a columnar grain model with three different orientations. The deformation mechanisms identified, including dislocation slip, grain-boundary-mediated plasticity, deformation twins and martensitic transformation, are in agreement with previous studies. In 〈110〉 columnar grains, the deformation is dominated by twinning, which nucleates primarily from the grain boundaries by successive emission of twinning partials and thickens by jog nucleation in the grain interiors. Upon arrest by a grain boundary, the twin may either produce continuous plastic strain across the grain boundary by activating compatible twinning/slip systems or result in intergranular failure in the absence of compatible twinning/slip systems in the neighboring grain. Multiple twinning systems can be activated in the same grain, and the competition between them favors those capable of producing continuous deformation across the grain boundary.