Modelling Rapid Solidification Using Atomistic and Continuum Methods

Abstract

<p>Free solidification molecular dynamics simulations were used to study solute trapping behaviour in the Ni-Cu alloy system. The segregation coefficient, K, as a function of crys- tallization rate was compared with several theories of trapping and, in agreement with a model proposed by Sobolev, it was found that complete trapping (K=1) occurs at a finite velocity. In order to gain further insight into the thermodynamic and kinetic factors affect- ing solute trapping, forced velocity phase field crystal (PFC) simulations were performed on a model binary alloy. We find that the complete trapping limit only occurs if a com- bination of wave-like and diffusive dynamics equation of motion of the PFC alloy model. Finally, an amplitude expansion analysis of the PFC formulation for constant velocity so- lidification was performed and an analytic expression for the complete trapping limit and solute drag was obtained.</p>