Alloying effect of titanium on WCp/Al composite fabricated by coincident wire-powder laser deposition

Abstract

Combined wire and powder deposition by laser (WPDL) has proven to be a promising method for the fabrication of Metal Matrix Composite (MMCs) materials. In this paper, aluminum matrix composites were fabricated by the WPDL method, where WC powder was fed from a coaxial nozzle, while aluminum wire was fed from a lateral nozzle into a laser generated melt pool. It was found that the WC particles had dissolved into the aluminum matrix as a reinforcement phase, which led to the formation of Al4W compounds, W2C carbides and Al4C3 carbides within MMC. The presence of the needle-like Al4C3 was detrimental to the mechanical properties of the MMC, due to its brittle nature. Through powder feeding with Ti and WC particles simultaneously during WPDL, laminated aluminum matrix compounds were produced under optimized parameter setup. XRD, SEM and TEM were employed to analyze microstructural features of the MMC. It was found that the formation of the brittle Al4C3 carbide was inhibited in MMC due to the alloying effect of titanium. The various phases of MMC identified include Al, WC, W, TiAl3, TiAl, Ti3Al and Al4W. The microstructural features of the interface between the reinforcement phase of WC ceramic and the aluminum matrix were examined.