Microstructure, formation mechanism and property characterization of Ti + SiC laser cladded coatings on Ti6Al4V alloy

Abstract

Surface modification of Ti6Al4V alloy was conducted by additive manufacturing using ball-milling treated mixture of Ti and SiC powder particles. Two laser cladded layers of 90%Ti + 10%SiC and 80%Ti + 20%SiC were deposited onto the Ti6Al4V substrate by single channel feeding system. This single channel feeding process using the ball-milled Ti+SiC powder mixture could offer a more homogeneous SiC distribution and thus cause a better fluidity during the laser cladding process. The microstructures of the cladded layers were analyzed by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). An X-ray diffraction (XRD) and a transmission electron microscope (TEM) were used for the determination of the phase products. The Vickers hardness of the cladded coatings was measured by H450-SVDH microhardness tester. Chemical reactions took place between the Ti and SiC particles in the composite layers, and the reaction products consisted of TiC and Ti5Si3. The average three-point bending strength of the sample from the Ti6Al4V substrate to the 80%Ti + 20%SiC coating was 515 MPa at room temperature. The 80%Ti + 20%SiC cladded layer increased the hardness of the Ti6Al4V matrix from 339.1 HV to 932.2 HV. As a consequence, the wear resistance was improved remarkably.