Incorporating density jumps and species-conserving dynamics in XPFC binary alloys

Abstract: This work presents a consistent formulation of the structural phase-field-crystal model of substitutional binary alloys that allows for the description phases of unequal densities, a key feature in solidification. We further develop the dynamics of the model to be consistent with conserved Langevine dynamics in the true governing species densities. Additionally, this work expands on the ability to control pressure, so far only implemented in pure materials, to binary alloys by improving the control system that controls pressure from previous work. We study the equilibrium properties of the new model, and demonstrate that control of pressure can drive various kinematic microscopic processes in materials such as grain boundary pre-melting, phase instability, and grain or inter-phase boundary motion.