Temperature-induced phase transformation of Fe1-xNix alloys: molecular-dynamics approach

Abstract

Using molecular-dynamics simulation, we study the temperature induced bcc/fcc phase transformation of random Fe1−x Ni x alloys in the concentration range of x ≤ 40 at%. The Meyer-Entel potential describes faithfully the decrease of the transition temperature with increasing Ni concentration. The austenite transformation proceeds by homogeneous nucleation and results in a fine-grained poly-crystalline structure. The transformation follows the Nishiyama-Wassermann orientation relationship. The martensite phase nucleates at the grain boundaries (heterogeneous nucleation). Even for the largest crystallite studied (2.75 × 105 atoms) the back-transformation results in a single-crystalline grain containing only a small amount of defects. The morphological changes in the transformed material show no significant dependence on Ni content.