在室温下利用纳米压痕测试技术研究了峰值载荷和加载速率对U65Fe30Al5新型非晶合金蠕变行为的影响规律。结果表明,随着峰值载荷和加载速率的增加,在相同蠕变时间内,蠕变位移呈增大趋势,但当加载速率高于特定阈值时,蠕变位移不再增大。通过蠕变经验公式拟合发现,蠕变过程的应力指数随峰值载荷的增加不断变大,但随加载速率的增加先减小后基本恒定。与常规晶态合金相比,U65Fe30Al5非晶合金具有更大的应力指数,这反映出后者内部结构中富含自由体积。
Uranium is a valuable nuclear fuel material, but this application is unavoidably handicapped by the easy creep behavior of the metal caused by the combination of stress and irradiation in nuclear reactor. Uranium-based amorphous alloys, as a kind of potential new materials in the nuclear industry, would be challenged by this issue when used in such situation. However, creep properties of these materials have not been reported in the previous studies. In order to preliminarily investigate the creep phenomenon derived from stress function, this work is performed to study the ambient creep behavior of a new amorphous alloy U65Fe30Al5. This alloy was tested by using a nanoindentation technique under different peak loads and loading rates. The results indicate that the creep displacement gradually increases with either the peak load or the loading rate in equal creeping time, but this tendency vanishes when exceeding a critical loading rate. The fitting based on an empirical creep equation reveals that the stress exponent of the alloy ascends when raising the peak load, and firstly declines with the loading rate and then keeps constant above the critical rate. Compared with conventional crystalline alloys, the U-Co-Al alloy shows a larger stress exponent, reflecting the possible existence of rich free volume in the amorphous alloy.
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