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

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 [1]) it is possible to follow the nucleation and further growth of the martensite structure (bee) 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 (fee) 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.