Unconventional non-uniform local lattice distortion in dilute Ti-Mo solid solution
Unconventional non-uniform local lattice distortion in dilute Ti-Mo solid solution
复制标题
稀钛钼固溶体中非常规非均匀局部晶格畸变
DOI：
10.1016/j.actamat.2020.07.033
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发表时间：
2020
期刊：
影响因子：
9.4
通讯作者：
Yang Rui
中科院分区：
文献类型：
--
作者：
Hu Qing-Miao;Yang Rui
在稀金属固溶体中，置换溶质原子引起的局域晶格畸变（LLD）被认为是均匀的，因为溶质原子被假定占据高对称性的晶格位置而不破坏晶格的点群对称性。与传统的观点相反，本文报道了Ti-Mo固溶体中的替位Mo原子占据了偏离中心的位置，而不是高对称性的晶格位置，导致了高度非均匀的LLD，我们的第一性原理计算证明了这一点。偏离中心占据和非均匀LLD的物理基础是Mo原子简并dd态的Jahn-Teller分裂。预测了非均匀LLD的固溶体。非均匀LLD的存在对基于均匀LLD和球应力张量假设的经典固溶体硬化模型在这类固溶体中的应用提出了挑战。这项工作也质疑了传统的观点，即金属固溶体中的元素替代溶质原子不应该引起滞弹性弛豫和内耗。
The substitutional solute atom induced local lattice distortion (LLD) in dilute metal solid solution was believed to be uniform because the solute atom was supposed to occupy the high symmetry lattice site without breaking the point group symmetry of the crystal lattice. Contrary to this conventional picture, we report in this paper that substitutional Mo atom in Ti-Mo solid solution occupies an off-center position instead of the high symmetry lattice site and leads to highly non-uniform LLD, as evidenced by our first principles calculations. The physics underlying the off-center occupation and non-uniform LLD are shown to be the Jahn-Teller splitting of the degenerateddstates of Mo atom. With which, the solid-solutions suffering from non-uniform LLD are predicted. The non-uniform LLD challenges the application of classical solid solution hardening model based on uniform LLD and spherical stress tensor assumption to this kind of solid solutions. This work also questions the traditional view that elementary substitutional solute atoms in metal solid solutions should not induce anelastic relaxation and internal friction.