CrMoNbTiV_x 难熔高熵合金高温氧化膜的组织特征及演化规律

CrMoNbTiV_x(x = 0, 0. 2, 0. 4, 0. 6 and 0. 8) refractory high entropy alloys with different V element contents were prepared, and their high-temperature oxidation resistance was tested at 800 ℃. Microstructure characteristics and evolution of the oxide film formed on the surface of the alloys were studied. The results show that after oxidation at 800 ℃ for different time, the CrMoNbTiV_x alloys with different V element contents form different oxidation products, and the formation of needle shaped V₂Nb₆O₁₉ oxide significantly reduces the oxidation resistance of the alloys. As the content of V element decreases, the thickness of the surface oxide film on the alloys becomes thinner, the thickness of the surface oxide film on the CrMoNbTiV_{0. 8} and CrMoNbTi alloys after 100 h of oxidation is 40 μm and 16 μm, respectively, the needle shaped V₂Nb₆O₁₉ oxide in the alloy oxide film decreases, and the dense Ti₄Cr₃Nb₃O₂ oxide and CrVNbO₆ oxide increase, reducing the internal oxidation of the alloy and thereby improving its oxidation resistance. When the V content is 0, the loose oxides in the CrMoNbTi alloy disappear, the oxide film is composed of dense TiO₂, Ti₄Cr₃Nb₃O₂, and a small amount of MoO₃ oxide, and therefore the oxidation resistance of the alloy is greatly improved.