Mahjoub Reza, Stanford Nikki
Future Industries Institute, University of South Australia, Mawson Lakes, SA, 5095, Australia.
Sci Rep. 2021 Jul 8;11(1):14159. doi: 10.1038/s41598-021-93703-w.
Although magnesium alloys are lightweight, recyclable and relatively cheap, they suffer from poor ductility. This can be improved by the addition of rare earth (RE) elements, and this is now a well-established criterion for wrought alloy design. It is notable that this behavior is largely restricted to the lanthanides, but no hypothesis is yet available to explain why other elements do not have the same effect. To answer this question, ab initio simulations of crystallographically complex boundaries have been undertaken to examine the electronic origin of the RE effect. While the electronic structure provided strong bonding between the RE elements and their Mg surroundings, local disruption in atomic arrangement at the grain boundaries was found to modify this effect. This work shows quantifiable changes in electronic structure of solutes resulting from grain boundary crystallography, and is suggested to be a contributing factor to the RE texture effect.
尽管镁合金重量轻、可回收且相对便宜，但它们的延展性较差。通过添加稀土（RE）元素可以改善这一问题，这现已成为锻造合金设计的既定标准。值得注意的是，这种行为在很大程度上仅限于镧系元素，但目前尚无假说来解释为什么其他元素没有相同的效果。为了回答这个问题，已经进行了晶体学复杂边界的从头算模拟，以研究稀土效应的电子起源。虽然电子结构在稀土元素与其镁周围环境之间提供了强键合，但发现晶界处原子排列的局部破坏会改变这种效应。这项工作展示了由晶界晶体学导致的溶质电子结构的可量化变化，并被认为是稀土织构效应的一个促成因素。
