Microstructural analysis of in-situ reacted Ti2AlC MAX phase composite coating by laser cladding

Abstract

Laser cladding was investigated as a method for the in-situ synthesis of Ti-Al-C MAX phase coatings due to its speed compared with standard powder metallurgy methods, localized high power density and small heat affected zone. A 2Ti:Al:C coating on a pure Ti substrate was targeted using a stoichiometric elemental powder ratio, resulting in a dense, well bonded composite coating of three layers totalling 1.33 ± 0.02 mm thick. A thin overlayer containing Ti2AlC MAX phase as the majority phase was produced at the coating surface, offering evidence for the feasibility of in-situ synthesis of a MAX phase by laser cladding with an elemental powder feed-stock. Quantitative phase analysis of XRD data indicated that the coating contained Ti2AlC as the majority phase at the coating surface, along with a uniform distribution of TiC0.64, Ti3Al and TiAl. A maximum Vickers hardness of HV 811 ± 11 was observed in the sub-surface region of the coating.