LASER Melt-Particle Injection Processing

Abstract

In situ metal matrix-ceramic composite layers on metal surfaces were formed by injecting metal carbide particles into laser melted pools. Injected layers up to 2 mm thick and containing up to 60 vol.-% carbides were produced. Injected surfaces exhibited high hardness, up to × 2·6 that of the base metal and erosion wear resistance of up to × 38 that of the base metal. Reasonable control of injected layer characteristics such as penetration depth and carbide distribution and volume fraction was demonstrated. Utilizing a laser beam oscillation technique, strips up to 10 mm in width were produced with a single melt pass. Microstructural and microhardness analysis showed variations in the degree of carbide dissolution across the injected layer. Test specimens designed for sliding contact and impact rub wear were fabricated with the oscillating beam technique. Preliminary results showed WC and TiC injected Ti-6Al-4 V alloy surfaces to be unsuitable for impact wear applications, but WC injected Inconel 625 appeared promising for certain sliding wear applications.