Tribology and high-temperature oxidation behaviors of NiCrBSiFe composite coatings on Ti6Al4V alloy by laser cladding

Abstract

In order to improve the high-temperature wear and oxidation resistance of Ti6Al4V alloys simultaneously, NiCrBSiFe composite coatings were deposited on a Ti6Al4V alloy by laser cladding. The microstructure, tribological properties and high-temperature oxidation resistance of the composite coatings were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and an energy dispersive spectrometer (EDS). The results indicate that the combination between cladding zone and substrate is metallurgical bonding, and the coatings have few pores, and are crack free and homogeneous structures. In situ synthetic TiC, TiB₂ and CrB particulates-reinforced γ-(Ni, Cr, Fe) matrix composite coatings are formed. The average micro-hardness of the composite coating is 950 HV_0.5, and it is almost three times that of the substrate. The laser clad coatings possess better tribology properties than Ti6Al4V alloys at all test temperatures (RT, 600 °C) and the formation of dense oxide layers played an important role in improving the high temperature oxidation resistance of Ti6Al4V alloys.