Effect of Nb on microstructure and properties of high entropy alloy coating by laser cladding

To enhance the high-temperature wear resistance and high-temperature oxidation resistance properties of Ti-6Al-4V, the TiAlNiCrVSiNbx high entropy alloy coating (HEA) was prepared on the Ti-6Al-4V substrate by laser cladding. The effects of Nb on the microstructure and properties of high entropy alloy coatings were mainly studied. The result indicated that the coatings are metallurgically bonded to the substrate. And the coatings consisted of body-centered cubic (BCC), face-centered cubic (FCC) and laves reinforced phases. The high-temperature wear resistance of the TiAlNiCrVSiNb 0.5 HEA coating is 20 times higher than that the Ti-6Al-4V alloy of at 800 ° C. The main wear mechanisms of the TiAlNiCrVSiNb 0.5 coating are oxidative and adhesive wear. After oxidation at 800 ° C for 500 h, the TiAlNiCrVSiNb 0.5 coating exhibited a mass gain of 10.45 mg/cm 2 , which is 1/6 that of under the same conditions. An oxide scale with multi-layer structures consisting of TiO 2 , NiCr 2 O 4 , Al 2 O 3 and VO 2 was generated on the coating. The oxide scale inhibited the inward diffusion of oxygen and the outward diffusion of alloy matrix elements.