A Modeling Study of Cyclical Phase Transformations

Abstract

Recent work has shown evidence of cyclical phase transformations taking place during mechanical alloying. Cyclical phase transformations resemble dynamic equilibrium in the sense that both equilibrium and non-equilibrium phases are simultaneously present during milling, but phase fractions vary during cyclical transformations. A brief thermodynamic and kinetic account is first discussed to establish the criteria for cyclical transformations. A two-dimensional molecular dynamic work is then presented to demonstrate cyclical phase transitions between an equilibrium and a non-equilibrium phase during mechanical alloying. A model binary crystal made of 57 Lennard-Jones atoms is studied to illustrate cyclical transitions between an equilibrium rhombus and a non-equilibrium square phase.