Study of the laser melting of pre-deposited intermetallic TiAl powder by comprehensive optical diagnostics

The process visualization has shown that the powder particles are melted and form relatively large size liquid droplets, 30-100 μm, that later on are integrated into the molten pool because of surface tension. Several small droplets are always detected well before the molten pool at the distance of about 200-300 μm. Their motion may be explained by the reactive pressure of evaporation and by the pressure of the expanding heated gas filling the space in between the particles.