Processing materials with lasers

Abstract

How can we make an alloy to fit a specific materials requirement? The oldest method of alloy fabrication, casting, has two inherent limitations: Phases with high melting points are difficult to melt; and the cooling of the alloys from the melt is slow, so that alloy segregation and phase separation have time to occur. The other traditional method, powder metallurgy, has helped with the second of these problems: Allowing the homogeneous melt to be cooled in tiny droplets makes it possible at least to limit segregation to the scale of the resulting powder particles. The laser, a clean source of thermal energy with high power density, can melt metallic and ceramic alloys to produce novel and useful microstructures; it also adapts well to automated processing techniques.