Origin of deflection of precipitates during interaction with a migrating twin boundary in magnesium alloys
Origin of deflection of precipitates during interaction with a migrating twin boundary in magnesium alloys
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DOI：
10.1016/j.commatsci.2018.08.020
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发表时间：
2018-11
影响因子：
3.3
通讯作者：
Fangxi Wang;Bin Li
中科院分区：
文献类型：
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作者：
Fangxi Wang;Bin Li
在 Mg 17 Al 12 沉淀物与迁移的 {1 0 1¯ 2} 孪晶边界相互作用期间，沉淀物上的偏转已被报道并解释为孪晶剪切的结果。然而，在实验报告中，偏离经典孪生行为的孪生边界的重要特征被忽略了。为了更好地理解这种偏转是如何产生的，在这项工作中，我们对析出物和移动孪晶边界之间的相互作用进行了原子模拟。对孪晶过程中的晶格转变、析出物-基体界面结构的演化以及析出物中选定原子的位移演化进行了详细分析。结果表明，尽管孪晶剪切大小为零，但当孪晶边界经过析出物时，仍然会发生偏转。这种偏转在相互作用过程中发生逆转，这是由于基底棱柱形转变引起沉淀物弛豫的结果，该转变沿母体的 c 轴产生拉伸应变。当析出物部分被孪晶吞没时，母体中的部分和孪晶中的部分经历不同的应变状态，从而产生与理论孪晶剪切无关的偏转。
During interaction between a Mg 17 Al 12 precipitate and a migrating {1 0 1¯ 2} twin boundary, a deflection on the precipitate has been reported and interpreted as a result of twinning shear. However, in the experimental reports, important features of twin boundaries that deviate from classical twinning behavior have been neglected. To better understand how such deflection is produced, in this work we performed atomistic simulations on interaction between precipitates and a moving twin boundary. Detailed analyses of lattice transformation during twinning, the evolution of the precipitate-matrix interfacial structure and the evolution of displacement of selected atoms of the precipitate were conducted. The results show that although the magnitude of twinning shear equals zero, deflection can still occur when the twin boundary is passing the precipitate. Such deflection is inversed during interaction as a result of relaxation to the precipitate caused by basal-prismatic transformation which generates a tensile strain along the c-axis of the parent. When the precipitate is partially engulfed by the twin, the portion in the parent and the portion in the twin experience different strain state, giving rise to the deflection which has nothing to do with the theoretical twinning shear.