Wear properties of metal matrix composite layers prepared by high power laser on Ti-Al-V substrate

Two laser surface engineering techniques, laser cladding and laser melt injection (LMI), were used to prepare metal matrix composite (MMC) layers with a thickness of about 1 mm, and volume fractions of ceramic particles of approximately 25-30%. The laser melt injection process was implemented to fabricate WC/Ti-6Al-4V and TiB₂/Ti-6Al-4V MMC layers, when additional material in the form of ceramic particles is injected into the molten substrate with only a limited interaction with the laser beam. As a result, a microstructure characterized by hard ceramic particles distributed in a metal matrix with very strong bonding is formed in the surface layer of the treated metal. TiB₂/Ti-6Al-4V MMC layers were produced in situ on Ti-6Al-4V substrates by conventional laser cladding. A mixture of TiB₂/Ti powders has been used as a precursor to obtain two microstructurally distinct layers, namely eutectic and primary TiB particles dispersed in Ti-6Al-4V matrixes. Sliding wear properties of these MMC layers were studied at boundary lubrication conditions and compared with the wear of the substrate materials. The observed wear mechanisms are summarized with the layers exhibiting excellent interfacial bonding, coupled with dramatically improved tribological properties expressed through a relative wear resistance value, ranging from 350-540.