Аннотация:The energy balance of laser beam buildup welding of powders is analyzed. Comparison of the obtained results with the experimental data shows that a significant portion of the absorbed power of the laser beam is consumed for evaporation the of powder. A procedure of selection and optimization of laser beam buildup of powder is proposed. It is established that the thermal conductivity and thermal diffusivity of powder can increase significantly within its melting owing to subsequent formation of thermal contact between the melt and underlying layer of powder particles. The range of the Péclet numbers corresponding to high efficiency of laser beam buildup welding of powders is determined.