Kinetic Simulation of Early Precipitation Behavior of Mg-Re Binary Alloy During Aging Process

Abstract

Controlling of the precipitation behavior has a crucial role for the development of high-performance Magnesium-rare earth (RE) alloys. However, precipitation happens in small-length and long-time scales, make it difficult to be analyzed by experimental characterization techniques. So, it still hasn’t established a comprehensive understanding for the early stage of precipitation. Here, we combine both advantages of 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. Similar [0001] morphologies compared with HAADF-STEM observation have been obtained in our simulation. We further studied the atomic structure and thermodynamics of the Y cluster systemically by tracing the Y atoms and comparing with DFT calculations. Our simulation 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.

Keywords: Mg-RE alloys, kinetic Monte Carlo method, DFT calculation, cluster