Laser-Pulsed Heating of Aluminum: Cavity Formation at the Surface

Laser evaporative heating of aluminum surface is modeled numerically and mushy zone formation across the solid-liquid and the liquid-vapor phases is introduced in the model study. Temperature rise in the irradiated region and the cavity formation during the laser heating pulse are predicted. Temperature-dependent properties are introduced during the simulations. Oxygen diffusion into the substrate material is considered during the laser heating process while employing temperature-dependent diffusion coefficient. An experiment resembling the simulation conditions is carried out and the morphology of the cavity produced at the surface of the laser-irradiated region is examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). It is found that the depth of liquid phase increases significantly with the progressing time and the size of the mushy zone across the solid-liquid phase is smaller than that of across the liquid and the vapor phases. The cavity depth, observed from the SEM and AFM micrographs, is shallow and similar to those predicted from the numerical simulations.