Molecular-dynamics study of martensitic transformations in sintered Fe-Ni nanoparticles
Nanocrystalline metals with grain sizes in the nanometer range often have interesting properties which differ from usual polycrystalline samples or single crystals. Here we report on the first molecular-dynamics simulations of martensitic transformations-i.e. structural transformations from fee to bcc-in sintered Fe-Ni nanoparticles. The atomic interactions were described by an embedded-atom method (EAM) potential specially designed to model the Fe-Ni system. Simulations were carried out by applying a constant pressure and temperature ensemble (NPT ensemble) to 32 nanoparticles each containing slightly more than 1000 atoms. The nano-particles initially were placed with random crystallographic orientation on an fcc lattice such that the particles attract each other. After relaxation for 0.58 ns at a temperature of 800 K and a pressure of 0 GPa a polycrystalline sample with a density just about two percent larger than that of a perfect single crystal was achieved. Subsequent cooling towards low temperatures allows the study of the temperature-induced martensitic transformation at pre-existing defects. (C) 2002 Elsevier Science B.V. All rights reserved.
martensitic transformation fe-ni nanoparticles polycrystalline sample molecular-dynamics simulations eam sintering process