Large-scale molecular-dynamics study of the nucleation process of martensite in Fe-Ni alloys

Abstract

High-performance large-scale molecular-dynamics (MD) simulations provide an atomistic insight of the nucleation process in Fe80Ni20. With the MD code SPASM (Scalable Parallel Short-range Molecular Dynamics) it is possible to follow the nucleation and further growth of the martensite structure (bcc) for more than one million atoms. The simulations show that the nucleation process is heterogeneous, at pre-existing defects. Further growth of the martensite structure into the austenite matrix (fcc) forms a typical twin structure on the nanoscale. Analysis of energy barriers between the martensite and the austenite can be used to interpret the nucleation process.