Twin suppression by atomic scale engineering of precipitate-matrix interfaces
Twin suppression by atomic scale engineering of precipitate-matrix interfaces
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DOI：
10.1016/j.actamat.2023.118797
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发表时间：
2023-02
期刊：
影响因子：
9.4
通讯作者：
X. Jin;C. Wang;S. Milenkovic;I. Sabirov;I. Beyerlein;M. Pérez-Prado
中科院分区：
文献类型：
--
作者：
X. Jin;C. Wang;S. Milenkovic;I. Sabirov;I. Beyerlein;M. Pérez-Prado
研究了溶质在颗粒-基体界面的偏聚对时效镁合金孪晶活动的影响。为此，首先将二元Mg-8Al合金（重量%）和两种三元Mg-8Al-1 Zn和Mg-8Al-1Ag合金（重量%）均质化，然后进行时效，以获得可比较的沉淀物分布。在二元合金中的颗粒-基体界面被观察到是干净的，而Zn和Ag原子偏析明显存在于三元合金的界面处。室温微柱压缩试验进行了在均匀化和老化条件下的三种材料的拉伸孪晶的有利取向的晶粒的调查。然后通过电子显微镜表征孪晶和滑移的活化。这项研究表明，虽然在二元合金沉淀没有导致任何重大变化的孪生活动，特别是，它并没有阻止形成厚的孪生laminae涵盖整个宽度的测试微柱，急剧减少的孪生活动发生在老化的三元合金。在后者中，应变导致形成属于一个单一的变种，狭窄的双laminates，偶尔逮捕在内部的微柱。我们认为，在时效三元合金中孪晶体积分数的急剧减少可能是由于Zn和Ag的偏析，这将阻碍在这样的界面处的再形核，从而抑制孪晶的传播的颗粒-基体界面能的降低。
This work aims to investigate the influence of solute segregation at particle-matrix interfaces on the twin activity of aged Mg alloys. With that purpose a binary Mg-8Al alloy (wt%) and two ternary Mg-8Al-1 Zn and Mg-8Al-1Ag alloys (wt%) were first homogenized and then aged in order to obtain comparable precipitate distributions. Particle-matrix interfaces in the binary alloy were observed to be clean, while Zn and Ag atomic segregation was clearly present at the interfaces of the ternary alloys. Room temperature micropillar compression tests were carried out in grains with favorable orientations for tensile twinning in the homogenized and the aged conditions for the three materials under investigation. The activation of twinning and slip was then characterized by electron microscopy. This study shows that while in the binary alloy precipitation did not lead to any major changes in the twinning activity and, in particular, it did not prevent the formation of thick twin lamellae encompassing the entire width of the tested micropillars, a drastic reduction of the twin activity took place in the aged ternary alloys. In the latter, straining led to the formation of narrow twin lamellae belonging to a single variant, and occasionally arrested at the interior of the micropillars. We propose that the drastic reduction of the twin volume fraction in the aged ternary alloys may be attributed to the decrease of the particle-matrix interface energy due to Zn and Ag segregation, which would hinder re-nucleation at such interfaces, thus suppressing twin propagation.