Effect of NiCrBSi content on microstructural evolution, cracking susceptibility and wear behaviors of laser cladding WC/Ni–NiCrBSi composite coatings

•Ni-based composite coatings were prepared by laser cladding.•With the addition of NiCrBSi, microstructure of the coatings presents the obvious difference.•As the content of NiCrBSi rises, microhardness is increased while fracture toughness is reduced.•As the content of NiCrBSi rises, wear morphology and wear mechanism present the regular change.•The appropriate addition of Ni (21%) can contributes to improving wear resistance of the coating.

Ni-based composite coatings were produced on the Ti6Al4V substrate by laser cladding 30 wt.% WC/70 wt.% (Ni–NiCrBSi). The microstructural evolution and mechanical properties were investigated in details. The results indicated that the coating (70 wt.% Ni) was mainly composed of WC and TiC as reinforcements, α(Ti), TiNi and Ti2Ni as the matrix. Two new phases (W, Ti)C and Ni3B were formed in the coating (21 wt.% Ni–49 wt.% NiCrBSi). When the content of NiCrBSi was further increased to 63 wt.% and 70 wt.%, the matrix was transformed into TiNi and TiNi3, and microstructural uniformity was also improved. As the contents of NiCrBSi were varied (0 wt.%, 49 wt.%, 63 wt.%, 70 wt.%), the average microhardness of the coatings was increased gradually (745 HV0.1, 976 HV0.1, 1046 HV0.1 and 1107 HV0.1), however fracture toughness presents the opposite change trend (4.20 MPa m1/2, 3.57 MPa m1/2, 3.02 MPa m1/2 and 2.92 MPa m1/2). Wear mechanism was also changed from the micro-cutting into the mixture of the micro-cutting and the brittle debonding, into the brittle debonding. The appropriate addition of Ni (21 wt.%) into the 30 wt.%WC-NiCrBSi cladding material was favorable to the improvement in wear resistance of the coating.