Atomistic mechanism for whole-field distortion of the substitutional solid solutions

The exploration of lattice distortion is of great significance to design and improve the substitutional solid solutions (SSSs). However, the distortion caused by substitution atoms is not well understood. We propose the atomistic mechanism and establish the corresponding theoretical framework that physically describes the distortion of general SSSs. The consideration is the local distortion propagates from the lattices containing substitution atoms to the bulks. Specifically, the local anisotropic lattice distortion is described by the atomic model based on the minimum energy principle, the non-uniform propagation of the local distortion is expressed by the one-dimension atomic chain model, and the whole-field distortion of SSSs is predicted by superimposing the distortion in the independent atomic chains. The framework is applied not only to predict the lattice constants, track each atoms equilibrium position, but also to estimate the distortion resistance of SSSs, and is validated via ab initio simulations of various SSSs with different types and contents substitution atoms. The research clarifies the origin mechanism and the universal laws of dilatation and lays the fundament for revealing the strengthening mechanism of SSSs.