Direct laser cladding of the silicide dispersed titanium aluminide (Ti45Al5Nb0.5Si) composites

Abstract

The present study concerns development of titanium silicide dispersed titanium aluminide composite with addition of 5 wt.% and 10 wt.% Si in Ti45Al5Nb0.5Si base alloy by direct laser cladding under varied process parameters. 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 develop a coupon with a dimension of 10 mm × 10 mm × 4 mm. The effect of process parameters (applied power, scan speed and powder feed rate) on the depth and integrity of the clad zone, microstructures and microhardness have been studied in details to optimize process parameters. Addition of Si leads to formation of micro-cracks in the microstructures under varied parameters. There are formations of different silicides (Ti5Si3, Ti7Al5Si12, TiSi2 and TiSi phases) in the microstructure of the base alloy with the presence α2 + γ phase. The microhardness of the clad layer increases with addition of Si. However, optimization of process parameters needs to be undertaken for the formation of defect free microstructure with improved hardness.