Local hardening and asymmetric twin growth by twin-twin interactions in a Mg alloy
Local hardening and asymmetric twin growth by twin-twin interactions in a Mg alloy
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DOI：
10.1016/j.jma.2022.11.008
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发表时间：
2022-12
影响因子：
17.6
通讯作者：
Krishna Yaddanapudi;Mariyappan Arul Kumar;Jiaxiang Wang;Xin Wang;T. Rupert;E. Lavernia;J. Schoenung;I. Beyerlein;S. Mahajan
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文献类型：
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作者：
Krishna Yaddanapudi;Mariyappan Arul Kumar;Jiaxiang Wang;Xin Wang;T. Rupert;E. Lavernia;J. Schoenung;I. Beyerlein;S. Mahajan
在这项研究中，孪晶相互作用的局部缺陷（如位错）和应力场的分布在镁合金中的作用进行了研究。变形Mg-3 wt.%合金中的共区（10 1 <$2）-（1 <$012）拉伸孪晶结用透射电子显微镜（TEM）对Y合金进行了分析。结果表明，碰撞（1 <$0 12）孪晶的形貌不对称，而接受（10 1 <$2）孪晶的非相互作用边界不规则。TEM图像的详细分析表明，II型金字塔[1 <$2 1 <$3]（1 2 <$12）位错集中在孪晶-孪晶结位置附近。在相互作用的孪晶畴内也观察到相同的位错，沿着有少量位错。从撞击（1 '012）双晶边界发出的位错具有边缘特征，并通过平行于基面的断层延伸。相反，与受体（10 1 <$2）孪晶相连的位错主要为螺旋取向且致密。基于弹粘塑性快速傅里叶变换的晶体塑性计算进行合理化观察到的孪晶形态和局部位错分布。模型计算表明，在两个双胞胎满足的交界处产生的局部应力场是负责实验观察到的位错浓度。计算的应力场是不对称的，相对于交界处，解释了观察到的不对称形态的撞击孪晶。总体而言，这些研究结果显示了孪晶-孪晶相互作用对位错分布以及孪晶微观结构的演变的强烈影响，因此，可以帮助推进对镁合金中孪晶及其对机械行为的影响的理解。
In this study, the role of twin-twin interactions on the distributions of local defects (eg, dislocations) and stress fields in a magnesium alloy is investigated. A co-zone (10 1¯ 2)-(1¯ 012) tensile twin junction in a deformed Mg-3wt.% Y alloy is analyzed using transmission electron microscopy (TEM). The results show that the morphology of the impinging (1¯ 012) twin is asymmetric, and the non-interacting boundary of the recipient (10 1¯ 2) twin is irregular. Detailed analysis of TEM images reveals that type-II pyramidal [1¯ 2 1¯ 3](1 2¯ 12) dislocations concentrate in the vicinity of the twin-twin junction site. The same dislocations are also observed inside the interacting twin domains along with a few dislocations. The dislocations emanating from the impinging (1¯ 012) twin boundary have edge character and are extended with faults parallel to the basal plane. In contrast, the dislocations connected to the recipient (10 1¯ 2) twin are predominantly screw orientation and compact. Elasto-viscoplastic fast Fourier transform based crystal plasticity calculations are performed to rationalize the observed twin morphology and local dislocation distribution. The model calculations suggest that the local stress fields generated at the junction site where the two twins meet are responsible for the experimentally observed concentration of dislocations. The calculated stress fields are asymmetric with respect to the junction site, explaining the observed asymmetric morphology of the impinging twin. Overall, these findings show strong effects of twin-twin interactions on the distribution of dislocations as well as the evolution of the twinned microstructure and as such, can help advance understanding of twinning in Mg alloys and their effect on mechanical behavior.