Kinetic simulation of early-stage precipitation behavior in Mg-RE binary alloys during aging process

Abstract

The precipitation behavior of magnesium-rare earth (Mg-RE) alloys plays a crucial role for their properties. However, the precipitation happens at small-length and long-time scales, making it challenging to be analyzed by state-of-the-art experimental techniques. Here, we combine the advantages of both molecular dynamic force fields on describing atom interactions and Monte Carlo method on describing diffusive events to develop an embedded atom method (EAM) potential based kinetic Monte Carlo (KMC) model. Using the proposed model, we simulated the formation and evolution of Y clusters in Mg-Y alloy formed by the vacancy mechanism, and rationalize the simulation results using aberration-corrected scanning transmission electron microscopy characterize. We conducted a systematic analysis of the atomic structure, the evolution kinetics and path of the Y cluster by tracing Y atoms and comparing with density function theory (DFT) calculations. Our work reveals that, all solute columns in a same cluster trend to grow along the [0001]_Mg direction synchronously. The method presented is not only used for the Mg-Y alloy but also other Mg-RE alloys such as Mg-Gd as illustrated in the last part of the paper.