Formation and autocatalytic nucleation of co-zone {10(1)over-bar2} deformation twins in polycrystalline Mg: A phase field simulation study
Formation and autocatalytic nucleation of co-zone {10(1)over-bar2} deformation twins in polycrystalline Mg: A phase field simulation study
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DOI：
10.1016/j.actamat.2018.04.043
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发表时间：
2018-07-01
期刊：
影响因子：
9.4
通讯作者：
Nie, J. F.
中科院分区：
文献类型：
--
作者：
Liu, H.;Lin, F. X.;Nie, J. F.
开发了相场模型来研究多晶镁中 {10 (1) over bar2} 孪晶的形成和自催化成核。研究发现，孪晶最有利于在具有最大负相互作用能的晶粒中成核。在此类晶粒内，能量上最有利的成核位置由集中在晶界附近的应力决定，这些应力与材料的弹性各向异性相关。此外，在由三个层状晶粒组成的结构中，中央晶粒中有一个传入孪晶，模拟结果表明，在自催化成核之前，传入孪晶通常具有透镜状形状。进入孪晶尖端周围的应力场在自催化成核中起主要作用。当孪晶在相邻晶粒中成核后，传入和传出孪晶同时演化，并且传入孪晶的形状逐渐从透镜状变为平行板状。在中心晶粒的晶体取向和施加的应变保持不变的情况下，孪晶成核的驱动力随着晶界上的取向差（高达 90 度）的增加而减小。进一步推导出，多晶结构的预先存在的应力场和待成核孪晶的本征应变之间的相互作用能值在数学上与孪晶的解析剪切应力相关。 (C) 2018 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
A phase-field model is developed to study the formation and autocatalytic nucleation of {10 (1) over bar2} twins in polycrystalline Mg. The twins are found to nucleate most favourably in grains with the most negative interaction energy. Within such grains, the energetically most favoured nucleation site is determined by stresses concentrated near the grain boundaries that are related to the elastic anisotropy of the material. Furthermore, in a structure consisting of three lamellar grains with an incoming twin in the central grain, the simulation results show that before autocatalytic nucleation, the incoming twin often has a lenticular shape. The stress field around the tip of the incoming twin plays the major role in the autocatalytic nucleation. After a twin has nucleated in the neighbouring grain, the incoming and the outgoing twins evolve simultaneously, and the shape of the incoming twin gradually changes from lenticular to parallel-sided plate. Under the condition that the crystallographic orientation of the central grain and the applied strain remains unchanged, the driving force for twin nucleation decreases with increasing misorientation (up to 90 degrees) across the grain boundary. It is further derived that the interaction energy values between the pre-existing stress field of the polycrystalline structure and the eigenstrain of the to-be-nucleated twin is mathematically related to the resolved shear stress of twins. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.