Modeling of controlled synthesis of intermetallic coatings

Abstract

Composite materials and coatings creation in modern combined technologies is perspective direction in the science when exothermic synthesis and electron beam or laser treatment are used together. Similar multifactor technologies demand the employment of mathematical modeling. In this work, two-dimensional model of the formation on the ferrous substrate of intermetallic coating from the powders Ni and Al is suggested. The model takes into account the heating by moving energy source corresponding to electron beam and the staging of chemical conversion. Due to small thickness of the treated layer temperature and composition distributions along the coating depth are not analyzed in a first approximation. However, the possibility of intermixing of materials of the coating and substrate and corresponding chemical reactions are taken into consideration for the temperature close to the melting temperature. The model was realized numerically. The distributions of the temperature and concentrations of individual species and new phases are studied for different time moments. It was shown that multi-phase coating forms in the conditions under study. It is possible to control the phase composition of the coating varying the composition of initial powders and treatment parameters. Self-sustained regime does not realize because heat losses to the substrate are high. This corresponds to experimental data. Effective properties of the coating could be evaluated for quasistationary stage that establishes quickly for each pass of electron beam.