Fundamental mechanism of BCC-FCC phase transition from a constructed PdCu potential through molecular dynamics simulation

摘要

An n-body PdCu potential is constructed under the framework of the embedded-atom method and is realistic to reproduce phase stability of PdCu phases. Based on this PdCu potential, two interface models with the Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS) relationships are established to reveal the kinetics and thermodynamics of the BCC-FCC phase transition through molecular dynamics simulation. It is found that the BCC - FCC phase transition should include the stages of nucleation, growth, and adjustment, and that the slip of edge dislocation of 1/6a(BCC)[0 (1) over bar 1] on (0 1 1 )(BCC) planes fundamentally brings about the nucleation of the FCC phase. Simulations also reveal that the lower energy difference between interface energy and surface energy could serve as the driving force of the nucleation of the FCC phase and intrinsically bring about the BCC - FCC phase transition in the interface with the NW orientation. The different behaviors of the BCC-FCC interface models with the NW and KS relationships are discussed in terms of kinetics and thermodynamics, which could provide a deep understanding of the BCC-FCC phase transition.