Numerical modeling of laser sintering of two-component powder mixtures

The process of direct sintering of metal powders induced by laser radiation is investigated. A two-component mix of powders consisting of low- and high-melting components is considered. The model is based on a self-consistent nonlinear equation of continuity for volume fractions of low- and high-melting components of the mixture and on the equation of energy transfer in the melt-powder mixture system. It includes the motion of hard particles due to shrinkage associated with the changed density of the powder mixture and with convective fluxes caused by the forces of surface stress and gravitation. The liquid flow is determined by the Darcy law of filtration. The effect of the finite width of the region of phase transition of the high-melting powder has been detected. The rate of melting zone expansion is shown to depend on both the parameters of laser radiation (beam power) and on the physical characteristics of the substance of particles, and to grow with the increase in penetrability or phase transition heat. A diagram of the evolution quality of the melting front is obtained, by which it is possible to predict the solution behavior depending on the parameters of the powder mixture (penetrability and melting heat).