EFFECT OF Y2O3 ON MICROSTRUCTURES AND WEAR RESISTANCE OF TiC REINFORCED Ti-Al-Si COATING BY LASER CLADDING ON TC4 ALLOY

Abstract

In this paper, TiC reinforced composite coatings were fabricated on TC4 alloy by laser cladding Ti,Al,Si, TiC and Y2O3 mixed powders. Microstructures and properties of the clad coatings with and without Y2O3 were discussed by comparative experiments. SEM, XRD and EDS were employed to discover the microstructures and the composition of phases. The hardness and wear resistance of the coatings were tested by the MM200 wear test machine and a HV-1000 digital hardness tester, respectively. The results showed that the coating was majorly composed of Ti5Si3, Ti7Al5[Formula: see text], Ti3AlC2, Ti3Al, Al3Ti, TiAl and Y2O3. The dilution zone exhibited a metallurgical bonding without pores and cracks. Compared with the TC4 substrate, the hardness and wear resistance of the coatings were heightened by 5–6 and 4.5–5.8 times, respectively. With 2.0[Formula: see text]wt.% Y2O3 addition, the microstructure of the coating was refined significantly, and the microhardness and dry sliding wear resistance were enhanced further. The effects of Y2O3 were attributed to heterogeneous nucleation of the residual Y2O3.