Microstructure of laser cladded carbide reinforced Inconel 625 alloy for turbine blade application

Inconel 625 - WC metal matrix composite is a very promising material for high temperature applications. In this study, microstructure investigation and phase composition of a mixture between Inconel 625 and fine tungsten carbide (φ≈0.64 µm) was performed by means of XRD, SEM with EDS and TEM with EDS. Two powder mixtures were prepared: 20 wt% of WC and 30 wt% of WC and deposited on Inconel 625 substrate by laser cladding obtaining a crack and pore free material. The high temperature of the process resulted in partial dissolution of WC in Inconel 625 matrix. In sample containing 30 wt% of WC appearance of topologically close-packed (TCP) phases was observed at grain boundaries. WC, W2C, NbC, W6C2.54 and (W,Cr,Ni)23C6 were detected by XRD. Angular residual carbides and spherical oxide precipitates were visible in both types of samples. Processes occurring during laser action were explained.