Microstructure and wear resistance of NiCrBSi laser clad layer on titanium alloy substrate

Laser cladding of NiCrBSi powders on Ti-6Al-4V alloy substrate was performed, and microstructure, microhardness and wear resistance of the clad layers were evaluated. Results show that the laser clad layer is divided into three regions: the clad, the dilution and the heat-affected zones. In the clad zone, line particles of TiB2, TiC and M-23(CB)(6) are distributed in the matrix of the primary gamma -Ni and the multi-phase eutectics consisting of gamma -Ni, Ni3B and silicides. Microhardness of the clad zone is very high, being approximately HV 1000. The dilution zone is a mixture of melted Ni-base and Ti-base alloys, and possesses a characteristic of directional crystallization. The heat-affected zone has an acicular martensitic structure, and the microhardness is HV 360-380. Compared to titanium alloy, the wear resistance of clad layer is improved. The mechanism of wearing of clad layer is a mixed type of slight peeling-off and abrasion. (C) 2000 Elsevier Science S.A. All rights reserved.