U-2.5% Nb合金表面的氢蚀特性

Hydriding Corrosion Characteristics of U-2.5% Nb Alloy Surface

利用气固反应系统对U-2.5%Nb合金表面进行了氢化,采用体视显微镜原位观察U-2.5%Nb合金的氢蚀,利用X射线衍射(XRD)、激光扫描共聚焦显微镜(LSCM)和扫描电镜(SEM)表征该合金氢化前后的成分及形貌。结果表明:在70℃、氢压为一个大气压的气氛中,U-2.5%Nb合金的氢化反应速率很高,氢化后形成了UH3化合物;合金表面氢蚀点边缘并非圆滑,而是呈条状优先形核相向外凸出。U-2.5%Nb合金表面氢化腐蚀的机制是:贫铌α相的氢蚀速率大于富铌γ1-2相的而优先发生氢蚀,随后贫铌α相之间的γ1-2相也相继发生氢蚀而连成一片后迅速长大。

The surface of U-2.5% Nb alloy was hydrogenated by gas-solid reaction system.Hydrogen corrosion of U-2.5% Nb alloy was observed in situ using a stereomicroscope,and the composition and morphology of the alloy before and after hydriding were characterized by X-ray diffraction（XRD）,laser scanning confocal microscopy（LSCM）and scanning electron microscopy（SEM）.The results showed that the hydrogenation rate of U-2.5% Nb alloy was very high at 70 ℃ and hydrogen pressure was one atmosphere,and UH3 compound was formed after hydriding.The edge of the hydrogen corrosion point on the surface of the alloy was not smooth,but rather the nucleus was preferentially nucleated and protruded outwards.The mechanism of hydrogenation corrosion on the surface of U-2.5% Nb alloy is that the hydrogen corrosion rate ofα-phase of niobium is higher than that of niobium γ1-2 phase and preferential hydrogen corrosion ofαphose occurs,and hydrogen corrosion of γ1-2 phase occurred one after another and quickly grew up.