Stability and formation of long period stacking order structure in Mg-based ternary alloys
Stability and formation of long period stacking order structure in Mg-based ternary alloys
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DOI：
10.1016/j.commatsci.2015.03.008
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发表时间：
2015-06
影响因子：
3.3
通讯作者：
Z. Liu;Dongyang Li
中科院分区：
文献类型：
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作者：
Z. Liu;Dongyang Li
长周期堆积有序(LPSO)结构是决定镁基三元合金强度和塑性的重要因素。在这项工作中，我们研究了10H LPSO结构的热力学稳定性，并与14H和18R LPSO结构进行了比较。提出了一个三聚体模型，用第一性原理计算预测了在Mg-xL-xS(XL=稀土，Ca，Sr和XS=Al，Zn，Cu，Ni)中形成LPSO结构的可能性。根据本征层错能、混合能和偏析能确定了LPSO结构的形成。降低本征层错能的元素对LPSO结构的形成是必不可少的。降低层错能有利于形成局域fcc层，从而吸引固溶质从hcp偏聚到局域fcc镁，形成L12团簇，最终形成LPSO结构。
Long period stacking ordered (LPSO) structure plays an important role in determining the strength and ductility of Mg-based ternary alloys. In this work, we investigated the thermodynamic stability of 10H LPSO structures in comparison with those of 14H and 18R LPSO structures. A trimer model was proposed to predict the possibility of forming LPSO structure in Mg–XL–XS(XL= Rare earth, Ca, Sr and XS= Al, Zn, Cu, Ni) with first-principles calculations. The formation of LPSO structure was determined based on the intrinsic stacking fault energy, mix energy and segregation energy. An element which decreases the intrinsic stacking fault energy is essential for the formation of LPSO structure. Decreasing the stacking fault energy favors the formation of local FCC layers, which would attract solid solutes segregating from HCP to local FCC Mg and forming L12cluster and finally the LPSO structure.