One-dimensional steady-state model for damage by vaporization and liquid expulsion due to laser-material interaction

A one-dimensional steady-state model describing the damage caused by materials removal by vaporization and liquid expulsion due to laser-material interaction is developed and presented. When vaporization occurs, there exists a discontinuity across the Knudsen layer of a few molecular mean free paths. This discontinuity is modeled by a Mott-Smith-type solution. The vaporization process creates a recoil pressure that pushes the vapor away from the target and expels the liquid. The materials are, therefore, removed in both vapor and liquid phases. The materials-removal rates are incorporated in the moving boundary immobilization transformation. The vapor phase is assumed to be optically thin so that its absorption of the high-energy beam is negligible. Closed-form analytical solutions are obtained and presented. The effect of heat-source power on removal rates, vaporization rate, liquid-expulsion rate, surface temperature, and Mach number are presented and discussed. Results are obtained for three different materials: aluminum, superalloy, and titanium.