Microstructures and mechanical properties of Nb nanoparticles modified Ni60 hard-facing alloy fabricated by laser metal deposition

Abstract

Crack-free samples were made from Nb nanoparticles modified Ni60 hard-facing alloy using laser metal deposition. Addition of Nb nanoparticles was carried out to modify the columnar dendrites and eutectic microstructures by providing large number of nucleation sites. The purpose of this study was to evaluate the effect of nanoparticles addition on cracking susceptibility of Ni–Cr–B–Si alloy. The results show that with addition of Nb nanoparticles, the cracking susceptibility reduced significantly with acceptable hardness loss. Large hard phases were refined and the columnar dendrites were converted to equiaxed grains, leading to a separated eutectic microstructure which restrain the initiation and growth of cracks. The study demonstrated a new method to tackle the cracking problem of laser manufactured Ni–Cr–B–Si alloys, accelerating the adoption of Ni–Cr–B–Si alloys on additive manufacturing applications.