The stability of y phase of U-Mo and U-Mo-X (X=Ti, V, Si) alloys, diffusion couples of U-Mo/Al and U-Mo-X/Al was studied, and effects of alloying elements and annealing process on y phase stability were investigated. The higher Mo content is, the more stable y phase is. The y phase of U-6. 5Mo-0. 5Si alloy is stable because the mixture enthalpy of U-Si is low, but Si addition into U-Mo alloy leads to formation of brittle phase USiT. The y phase of U-6. 5Mo-0. 5Ti or U-6. 5Mo-0. 5V alloys is unstable because the mixture enthalpy of Mo-Ti or Mo-V is low, and this leads to formation of solid solution or compounds and Mo dilution in y phase. As annealing temperature increasing from 500 ℃ to 600 ℃, y phase decreases by eutectoid decomposition, a phase increases, and some new Al-rich phases such as UA14, UM02 Al20 and U6 Mo4 Al43 are produced.%研究了U-Mo、U-Mo-X(X=Ti、V、Si)合金及U-Mo/Al、U-Mo-X/Al扩散偶界面层的γ相稳定性,探讨了合金元素和退火工艺对γ相稳定性的影响.结果表明:Mo含量越高,U-Mo合金的γ相稳定性就越高;U-6.5Mo-0.5Si合金的γ相稳定性较高,是因为U-Si混合焓较低,但加入Si易导致形成USix脆性相;而U-6.5Mo-0.5Ti和U-6.5Mo-0.5V合金的γ相稳定性较差,是因为Mo在Ti、V体系内具有较低的混合焓,易形成固溶体或金属间化合物,导致γ相贫Mo;随着退火温度从500℃升高至600℃,γ相发生共析分解,扩散层的γ相数量减少,α相增多,α相成为Al的快速扩散通道,促使形成UA14、UMo2 Al20和U6 Mo4 Al43等富Al相.
展开▼
