Spreading and solidification of metal-melt droplets under conditions of substrate submelting. Theory and model experiment

Spreading and solidification of metal-melt droplets upon their collision with a surface are of particular interest for thermal spraying, molding, melt spinning for obtaining amorphous and microcrystal powders, etc. The scenarios of the formation of splats (spread and solidified particles on the substrate) can be significantly different and are determined by thermophysical properties of materials of the particle and substrate, as well as by key physical parameters (KPPs): velocity $u_{p0}$, size $D_p$, and temperature $T_{p0}$ of the droplet and substrate $T_{b0}$ and the state of its surface. An attempt was made to theoretically and experimentally study the formation of splats for the case in which the substrate is submelted in the spot of the contact with the particle in the process of spreading and solidification of metal-melt droplets.