Mathematical simulation of laser induced melting and evaporation of multilayer materials

Using the laser induced remelting of a three-layer target Al+Ni+Cr as an example, the use of the dynamic adaptation for solving the multifront Stefan problem with explicit tracking of the melting and evaporation fronts is considered. The dynamic adaptation is used to construct quasi-uniform grids in regions with moving boundaries. The characteristic size of those regions may vary by several orders of magnitude in the process of computations. The algorithm used to construct the grids takes into account the varying size of the region and the velocity of the boundary motion, which makes it possible to automatically distribute the grid points without using fitting parameters. The mathematical simulation of the doping process using the melt with respect to the thick substrate and thin doping layers showed the importance of the sequencing of coatings. The computations showed that if the upper exposed layer is chromium, then it can completely evaporate or sublimate by the end of the pulse due to its heat-transfer properties. This can be easily changed if the doping layers are arranged according to the scheme Al+Cr+Ni. Then, the upper exposed layer is nickel, which is not so easily evaporated.