Atomistic-Scale Simulations on Grain Boundary Migration Mechanisms Involved in Metals and Alloys: A Critical Review

The mechanical properties of a material are affected by the kinetics and thermodynamics of the grain boundaries (GBs) present in their domain. Various research works, both experimental and simulation-based, have been undertaken to explore the relation between GBs and mechanical characteristics of materials, however, the underlying mechanism of GB growth or migration is still not well understood and requires additional research. Experimentally, the tracking of micro-evolution in GBs is a challenging task and to resolve this, atomistic-scale based molecular dynamics (MD) based simulations have emerged as a prominent tool for investigating the structure, kinetics, and thermal behaviour of GBs. Here in, the authors present a comprehensive overview of the research conducted on GB migration using MD based simulations. First, we discussed the various driving force (DF) methods utilised in MD simulations to cause GB migration. This includes artificial DF, curvature driven method, elastic DF, thermal gradient DF, Peach-Koehler DF method and random walk method. The concepts and underlying principles of each approach are then unveiled in detail. Next, a thorough examination of the principal discoveries of prior works conducted based on these approaches is showcased. The influence of grain boundary (GB) energy, faceted structure, grain growth, the type of driving force applied, temperature, and other relevant parameters has been thoroughly analyzed. The advantages and limitations of various approaches for studying GB migration are also pondered over. Finally, a summary of methods is given in conjunction with potential future directions.