Microstructure and wear properties of laser processed Ni based amorphous matrix coatings

Abstract

Ni_40·8Fe_27·2B₁₈Si₁₀Nb₄ (at-%) coating was deposited on mild steel substrate using high power diode laser cladding followed by laser remelting process. The phase composition and microstructures of the as cladded coating and remelted coating were analysed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The microhardness and wear properties of the coatings were also tested and analysed. It was observed that the remelted coating has an amorphous matrix embedded with some dendrites. The remelting of the coating increased the hardness of as cladded coating by ∼25%. The remelted coating exhibited a characteristically lower friction coefficient (0·21) than the as cladded coating (0·27) and the substrate (0·31). Significant increase in wear resistance was found for the remelted coating compared with the as cladded coating and the substrate under identical conditions.