Numerical modeling of laser sintering of two-component powder mixtures

Direct laser sintering of metal powders is investigated by numerical simulation. Two-component powder bed that contains a mixture of low- and high-melting particles is considered. The model is based on self-consistent non-linear continuity equations for volume fractions of the solid and the liquid particles and on energy transfer equations for the powder mixture. It includes the movement of the solid particles due to shrinkage because of the density change of the powder mixture and also the convective fluxes depend on surface tension and gravity forces. Liquid flow is determined by Darcy filtration law. The effect of surface settlement of the powder is obtained. The width increasing rate of the melting zone is depended both on the parameters of the laser radiation (on the power of the beam) and on the physical parameters of the particles' material, and it increases with the increasing of the penetrability or the increasing of the phase-transition heat. The increasing of the laser power under other factors being equal results in the acceleration of the melting front propagation. The evolutionary diagram which allows to predict the behavior of the solution depending on the parameters of the powder mixture (penetrability, melting heat) is presented.