【摘要】 针对U-Co与U-Fe体系中非晶形成能力最佳的合金U66.7Co33.3与U69.2Fe30.8,通过调整合金熔体的冷却速率获得一系列非晶样品,结合XRD与DSC技术研究了样品的相组成随冷却速率的演变规律。结果表明,这些合金在较高冷却速率下几乎都能够完全非晶化,而当冷速降低到一定程度时都会析出U6Mn型晶体相。相比而言,U-Fe合金形成完全非晶需要更低的临界冷却速率,从而直接证实U-Fe体系比U-Co具备更强的非晶形成能力,其原因是前者在非晶形成过程中兼具热力学与动力学优势。更多还原

【Abstract】 Because of having better corrosion resistance properties than crystalline uranium alloys,U-based metallic glasses show strong potential of applications in nuclear fields. U-Co and U-Fe are Ubased important base glass systems, from which almost all the reported multi-component U-based amorphous alloys derive. However, which system possessing higher glass forming ability is unclear yet. Therefore, the relationship between the glass formation and the solidification rate is studied on two glassy alloys U66.7 Co33.3 and U69.2 Fe30.8 in this work, which are the best glass former in the corresponding system. A series of amorphous samples were prepared by modifying the cooling rate of their melts, and then were measured by using XRD and calorimetric analysis technique. The results show that both alloys were able to nearly amorphize completely at higher cooling rate, and tended to segregate U6 Mn-typed crystalline phase when the cooling rate declined to some extent. In contrast, the U-Fe alloy needs a much lower critical cooling rate to achieve fully amorphous structure, directly demonstrating that U-Fe system possesses stronger glass forming capacity than U-Co. The reason for this conclusion is that the former system is of both thermodynamic and kinetic advantages for glass formation. This result can be applied as the foundation to exploit superior novel multicomponent U-based amorphous alloys.更多还原