Powder delivery behavior during laser solid forming from blended elemental powders

The delivery behavior of the elemental powder has important influence on the composition of as-deposited sample during laser solid forming (LSF) from blended elemental powders. In order to ensure the consistency of the elemental powders delivery processes, and further to realize the composition control, the delivery behavior of the elemental powder during LSF is investigated. Based on the analysis of gas-powder two-phase flow, a mathematical model is established to describe the motion of the powder particles inside and outside the nozzle, and the influence of the powder characteristics on the powder delivery behavior is investigated. It is found that both the powder particle exit velocity and the motion acceleration increase with the decrease of the powder particle size and density. The consistency condition for different elemental powders delivery process is obtained, which is the identity of the exit velocity of the elemental powders. Based on the consistency condition, the match relation among the elemental powder characteristics (including the particle size and density) can be obtained, which ensures the consistency in composition between the laser deposits and the premixed elemental powders during LSF from blended elemental powders.