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研究了淬火和时效2种状态的U-5.7%Nb合金,从室温(20℃)~800℃温度范围的准静态拉伸性能,及合金的变形和断裂行为。结果表明,不论淬火或时效状态的U-5.7%Nb合金,当温度高于200℃后,合金在室温下表现出的二次屈服现象将完全消失,并在400℃温度附近发生脆化,在700℃温度附近表现出明显的超塑性,其中淬火态合金性能的变化尤为明显。并对准静态拉伸、Hopkinson拉伸及爆炸膨胀环3种加载速率下,时效态U-5.7%Nb合金的组织结构进行了对比分析。结果表明,以不同应变速率断裂的时效态U-5.7%Nb合金,断口中心部位的韧窝比边缘部位相对明显,Hopkinson拉伸断口的晶粒大于准静态拉伸断口的晶粒,爆炸速率断裂的合金断口有剪切断裂、边缘开裂及局部夹杂脱落的现象。
The quenched and aged U-5.7% Nb alloys were investigated. The quasi-static tensile properties at room temperature (20 ℃) ~ 800 ℃ and the deformation and fracture behavior of the alloys were investigated. The results show that the secondary yielding behavior of the alloy at room temperature will disappear completely when the temperature is higher than 200 ℃ regardless of the quenched or aged U-5.7% Nb alloy and embrittlement occurs at around 400 ℃. 700 ℃ temperature near the obvious superplasticity, quenching alloy performance which is particularly evident. The microstructures of U-5.7% Nb alloy aged at different loading rates of static tensile, Hopkinson tensile and explosive expansion rings were compared. The results show that the dimples in the central part of the fracture are more obvious than the edge part in the U-5.7% Nb alloy aged at different strain rates. The grain size of the Hopkinson tensile fracture is larger than that of the quasi-static tensile fracture, The fracture of the alloy has shear fracture, edge cracking and partial inclusions shedding phenomenon.