Laser in-situ synthesizing Ti5Si3/Al3Ni2 reinforced Al3Ti/NiTi composite coatings: Microstructure, mechanical characteristics and oxidation behavior

To enhance the wear resistance and elevated temperature antioxidation of Ti6Al4V alloy simultaneously, Ni-20Cr powders with the addition of Al and Si were deposited successfully on its face by laser in-situ synthesizing. The microstructure, micro-hardness, wear, elevated temperature antioxidation of composite coatings were researched. The results show that the composite coatings are mainly composed of Ti5Si3/Al3Ni2 as reinforcing particles and Al3Ti/NiTi as intermetallic matrix, and had a metallurgical bonding with substrate. The average micro-hardness of composite coatings are 2.5-3 times higher than that of the Ti6Al4V alloy. Moreover, when the precursor composition is NiCr-40Al-20Si (wt.%), the composite coating presents a better wear resistance at room temperature (RT), which is twice higher than that of substrate because of superior hardness, strong intermetallic atomic bonding and toughness, because of the emergence of continuous dense Al2O3 scales, the composite coating presents an enhanced oxidation resistance at 800 °C.