Fabrication of CNTs–TiC–Ti2(Ni,Al)–Ni3Ti reinforced Ti-based composite coating by laser alloying processing

Abstract

In-situ formation of TiC, Ni3Ti and Ti2(Ni,Al) with CNTs reinforced Ti-based composite coatings were fabricated by laser alloying processing. The effect of laser specific energy on the microstructure, micro-hardness and wear property of the composite coatings were studied. The results showed that the composite coatings exhibited free from cracks and pores. Cypress leaf-like and flower-like TiC dendrites, as well as block-like Ti2(Ni,Al) and rod-like Ni3Ti intermetallic compounds were in-situ formed and distributed uniformly in the coating. With the increasing of laser specific energy, TiC dendrites coarsened and amount of TiC reduced. The micro-hardness and wear resistance of the coatings first increased and then decreased with the increasing of laser specific energy. When laser specific energy was controlled with 4.167–5 kJ/cm2, coatings with high micro-hardness and wear resistance were obtained. Wear resistance of the coatings were 2.3–6.9 times of that of substrate. Wear behavior of the dominant wear mechanism of the composite alloying coatings was adhesive wear, however, the Ti6Al4V substrate exhibited serious abrasive wear, adhesive wear and plastic deformation.