Microstructure and tribological properties of laser clad Ti 2Ni 3Si/NiTi intermetallic coatings

Abstract

Wear resistant Ti 2Ni 3Si/NiTi full intermetallic composite coatings with a microstructure consisting of ternary metal silicide Ti 2Ni 3Si primary dendrites and interdendritic Ti 2Ni 3Si/NiTi eutectic were fabricated on a substrate of 0.2%C low carbon steel by the laser cladding process using Ti-Ni-Si alloy powders as the precursor materials. Microstructure of the coatings was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Wear resistance of the laser clad Ti 2Ni 3Si/NiTi intermetallic coatings was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the Ti 2Ni 3Si/NiTi intermetallic coatings have excellent abrasive and adhesive wear resistance under dry sliding wear test conditions because of the unique combination of high yield strength and toughness of the intermetallic compound NiTi and the high hardness, strong covalent dominant atomic bonds and possible strong hardness anomaly of the ternary metal silicide Ti 2Ni 3Si with MgZn 2 type Laves crystal structure.