Laser clad Cr3C2–Ni composite coating on titanium alloys

Abstract

Cr3C2–Ni composite coatings were fabricated on Ti–6Al–4V substrate by laser cladding using powder mixture of NiCrBSiC alloy and Cr3C2. Results of the analysis show that the microstructure and microhardness of the coatings depend strongly on the specific laser energy. With a relatively low specific laser energy (133·3 J mm−2), Cr3C2 particles were partially dissolved into melted Ni based alloy, and the coating was formed of undissolved Cr3C2 particles and cannular Cr23C6 uniformly distributed in cellular γ-Ni and eutectic matrix. With a higher specific laser energy (266·7 J mm−2), more Cr3C2 particles were dissolved, and the coating consisted of γ-Ni, TiC dendrites and lamellar CrB. When the specific laser energy is 133·3 and 266·7 J mm−2, the microhardness of the coating is 500–700 HV and 700–1000 HV, respectively.