高熵合金Mo_(25)Nb_(25)Ta_(25)W_(25)的氧化行为

Oxidation Behavior of High Entropy Mo_(25)Nb_(25)Ta_(25)W_(25) Alloy

探究氧化物层的破裂和钼的氧化物挥发在高熵合金Mo_(25)Nb_(25)Ta_(25)W_(25)的氧化动力学中的作用机理。通过热压烧结制备了具有简单BCC结构的Mo_(25)Nb_(25)Ta_(25)W_(25)高熵合金。分别研究其在800、900和1 000℃下的氧化动力学行为,并对其氧化机理进行了初步描述。通过XRD、SEM和电子探针对氧化物进行表征。结果表明,在整个氧化温度范围内,氧化层中主要氧化产物为Ta_(16)W_(18)O_(94)和Nb_(14)W_3O_(47),具有一定的保护性。试样在800℃下遵循抛物线规律,随试验温度升高,生成的MoO_3挥发,氧化层变得疏松多孔,使合金在900℃的中期和1 000℃开始满足直线规律。

The action mechanism of oxide layer crack and volatilization of molybdenum oxides in the oxidative kinetics of high entropy alloy Mo（25 ）Nb25Ta25W25was described.An equal mole ratio Mo25Nb25Ta25W25alloy with a simple BCC structure was prepared by hot-pressing sintering.The oxidation behavior of the high entorpy alloy were analyzed at 800℃、900℃and 1 000℃,respectively,and the oxidation mechanism was expounded.The oxides were characterized by XRD,SEM and electron probe X-ray microanalyzer（EPMA）.The results reveal that at oxidation temperature range,the main oxidation products are Ta16W18O94and Nb14W3O47with some protection in the oxide layer.The kinetics of the tested samples follows the parabolic law at 800℃,while follows the linear law at the middle of 900℃and1 000℃,which are attributed to the volatilization of MoO3leading to oxide layer loose and porous at higher temperature.