Microstructural Evolution and Microhardness of Direct Laser Clad TiC Dispersed Titanium Aluminide (Ti45Al5Nb0.5Si) Alloy

In the present study, the effect of TiC additions (10 wt.% and 20 wt.%) on the microstructure and microhardness of direct laser clad Ti45Al5Nb0.5Si based titanium aluminide alloy has been undertaken. Direct laser cladding has been conducted using a high power (3 kW) fiber optic delivered Nd:YAG laser (with a beam diameter of 2 mm) using a 3-axis handling system in a layer by layer fashion to on Ti-6Al-4V substrate to develop a coupon with a dimension of 10 mm x 10 mm x 5 mm. Addition of TiC leads to formation of defect free microstructures under varied parameters, except a few processing conditions. There is formation of complex carbides (Ti2AlC, Ti3AlC2 and Ti2AlC) in addition to TiC phase in the microstructure of duplex a2+g phase. There is improvement in microhardness due to TiC addition, which increases with increased quantity of TiC. Laser power and scan speed influences the microhardness, however, powder feed rate did not influence it significantly.