The study of microstructure and propagation of the combustion wave of SHS in nanodimensional multilayer systems of Ni-Al with using molecular-dynamic simulation

Abstract

Computational experiments (CEs) on the molecular-dynamic simulation of the propagation of the combustion wave of the SH-synthesis process in a stack of alternating layers of nanoscale crystal lattices of Ni and Al atoms have been carried out. In the calculations are used two versions of the interatomic interaction potential in the “embedded atom model” (EAM) and the LAMMPS package taking into account parallel computings. As the results of computational experiments for two varieties of the EAM potential, a family of temperature profiles along the layers of the structure at successive instants of time (up to 40 ns) and the corresponding set of microsections (snapshots) of the layered structure are given. For large values of the initial heating temperature and the stoichiometric ratio of Ni and Al atoms in the SHS sample, the computational experiments were confirmed the heterogeneous SHS-reaction mechanism, referred to in scientific publications as “mosaic-dissolution-precipitation”. In addition, when under such conditions a combustion wave of SHS passes through, the effect of heat localization is observed with the establishment of a higher temperature in the final region of the sample compared with the initial region, as a result of which on the “plateau” of the temperature profile corresponding to 16 ns a smooth “dip” is observed. Then, at subsequent times, there is a continuation of combustion (more precisely, after combustion) in the inverse direction with the equalization of the temperature plateau corresponding to a higher temperature value of the final region of the SHS-sample.