M oNbVTa_x 系 难 熔 高 熵 合 金 的 高 温 氧 化 行 为 与 机 理

The oxidation test of MoNbVTa（_x x=0、0. 3、0. 5、0. 7 and 1）was carried out for different duration under atmosphere at 800 ℃，and effects of oxidation time and Ta contents on oxidation behavior and mechanism of the alloy were investigated. The results indicate that with increasing in oxidized time，the melt or vaporization of oxydate occurrs，leading to the thickening and cracking of oxidation layer. As Ta content increases，the unique slow diffusion effect of high entropy alloy is enhanced，and the diffusion of oxygen elements is suppressed，reducing volume fraction of V-rich area or easily oxidized region，as well as diffusion channel of oxygen，resulting in the enhancement of high temperature oxidation resistance. Moreover，Ta oxide possesses a higher chemical stability to reduce the cracking tendency，which improves the density of oxide layer and inhibits the diffusion cracking of oxidation layer.