Phase diagram of carbon-nickel-tungsten: A superatom model

Abstract

Carbon solubility in face-centered-cubic Ni-W alloys and the phase diagrams of Ni-W and C-Ni-W are investigated by means of first principles calculations and semigrand canonical Monte Carlo simulations. With density functional theory total energies as fitting data, we build a superatom model for efficient simulation. Multihistogram analysis is utilized to predict free energies for different compositions and temperatures. By comparing free energies of competing phases, we are able to predict carbon solubility and phase diagrams of C-Ni-W at different temperatures. A simple ideal mixing approximation gives qualitatively similar predictions.