Effect of Fe and Ni contents on microstructure and wear resistance of aluminum bronze coatings on 316 stainless steel by laser cladding

Aluminum bronze coatings with five different contents of Fe and Ni were successfully prepared on 316 stainless steel by laser cladding, aiming at improving wear resistance. Constituent phases, microstructure, microhardness and wear resistance of aluminum bronze coatings with different Fe and Ni contents were investigated using XRD, OM, SEM, EDS, microhardness tester and pin-on-disk wear-testing machine, respectively. Experimental results show that with appropriate laser processing parameters, the coatings are uniform and dense, in addition to good metallurgical bonding to the substrate. The coatings mainly consist of α-Cu matrix, γ2, β′, Cr-Fe and κ phase. The formation of these phases is explained in terms of the principles of thermodynamic metallurgy. The number of Cr-Fe phases increases with the addition of Fe and Ni, leading to the increase the heterogeneous nucleation sites and refining the microstructure. The microhardness of Cu-7Al-5Fe-5Ni coating is the highest, up to 281 ± 13 HV0.3, while the Cu-7Al-1Fe-1Ni coating with microhardness of 244 ± 12 HV0.3 exhibits the highest wear resistance. This phenomenon could be attributed to the fact that adding excess Fe and Ni into aluminum bronze would easily make hard reinforcing phases detach from the matrix and become debris, which could penetrate into the matrix and make lots of material loss, thus accelerating the wear process.