Twinning-induced plasticity with multiple twinning modes and disclinations in Mg alloys
Twinning-induced plasticity with multiple twinning modes and disclinations in Mg alloys
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DOI：
10.1016/j.ijplas.2023.103595
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发表时间：
2023-03
影响因子：
9.8
通讯作者：
Yipeng Gao;Lei Zhao;M. Zha;Chun-Feng Du;Zhen-Ming Hua;K. Guan;Hong Wang
中科院分区：
文献类型：
--
作者：
Yipeng Gao;Lei Zhao;M. Zha;Chun-Feng Du;Zhen-Ming Hua;K. Guan;Hong Wang
孪晶诱导塑性在确定密排六方金属（如Mg和Ti）的变形行为中起着关键作用，这是由于缺乏一般变形所需的五个独立滑移系。特别是，可以适应c轴应变（拉伸或压缩）的孪生模式是特别重要的，这是必要的互补变形模式，以< a>型位错。然而，只有有限类型的延伸孪晶，如{10 1 <$2}型孪晶，已明确确定在文献中，这是理论上不足以容纳复杂的变形与c轴延伸。利用拓扑缺陷理论，我们证明了在镁合金中，向错与{10 1 <$2}孪晶之间的反应可以形成另一种伸展孪晶模式，即{11 2 <$6}孪晶。基于变形空间的对称性，我们证明了{11 2 <$6}孪晶起源于相关变形路径的相互连接，它可以提供沿着c轴的5.2%的拉伸应变和沿着< 11 2 <$0>的4.5%的压缩应变。{11 2 <$6}孪晶的形成机制有三种，即直接形成、孪晶-孪晶相交和双孪晶，并通过实验表征和相场模拟相结合的方法进行了验证。本文的工作不仅为研究孪生诱导塑性提供了一种新的方法，而且为研究镁合金的变形机制和力学性能提供了新的思路。
Twinning-induced plasticity plays a critical role in determining the deformation behaviors of hexagonal close-packed metals (eg, Mg and Ti), due to the lack of five independent slip systems required for a general deformation. In particular, twinning modes that can accommodate c-axis strain (tensile or compressive) are especially important, which are necessary complementary deformation modes to< a>-type dislocations. However, only limited types of extension twins, eg,{10 1¯ 2} type twin, have been unambiguously identified in the literature, which is theoretically inadequate to accommodate a complex deformation with c-axis extension. Using topological defect theory, here we show that another extension twinning mode,{11 2¯ 6} twin, can be formed through reactions between disclinations and {10 1¯ 2} twins in Mg-alloys. Based on symmetry of the deformation space, we demonstrate that the {11 2¯ 6} twin originates from the inter-connection of correlated deformation paths, which can provide a tensile strain of 5.2% along c-axis and a compressive strain of 4.5% along< 11 2¯ 0>.{11 2¯ 6} twins can be formed through three formation mechanisms, ie, direct formation, twin-twin intersection, and double twinning, which are validated by a combination of experimental characterizations and phase field simulations. Our work not only suggests a symmetry-based method to analyze twinning-induced plasticity, but also provides a new insight into the deformation mechanisms and mechanical properties of Mg-alloys.