Molecular dynamics simulation of martensitic phase transformations in Ni-Al alloys

Using molecular dynamics (MD) simulation we investigate the structure, the thermodynamics and the kinetics properties of a model NiAl alloy with respect to the martensitic phase transformations (MTP). We observe a wide hysteresis in the temperature dependence of thermodynamics properties while cooling and heating of initially B2 alloy with a composition range from 60 to 65 at. % of Ni. The type of structural state of the alloy before and after the transformation can be well defined by means of pair radial distribution functions. The local structure development during the phase transformation is analyzed by the local order parameter which is based on a combined method of Voronoy tessellation with common-neighbor analysis. This local order parameter allows us to get a detailed localized picture of nucleation and growth of the new phases. MD simulation could successfully reproduce the MPT and the Ni content dependence of the MPT temperatures. First results indicate that a cylindrical defect strongly affects the MPT.