Development and characterization of composite Ni-Cr-C-CaF_2 laser cladding on gamma-TiAl intermetallic alloy

摘要

A process of laser cladding Ni-Cr-C-CaF_2 mixed powders to form a multifunctional composite coating on gamma-TiAl substrate was carried out. The microstructure of the coating was examined using XRD, SEM and EDS. The coating has a unique microstructure consisting of primary dendrite or short-stick TiC and block Al_4C_3 carbides reinforcement as well as fine isolated spherical CaF_2 solid lubrication particles uniformly dispersed in the NiCrAlTi (gamma) matrix. The average microhardness of the composite coatings is approximately HV 650 and it is 2-factor greater than that of the TiAl substrate.