Equal-channel angular pressing (ECAP) and mechanical machining were employed to introduce large plastic shear strain into bulk and the surface layer of a U-5.5wt.%Nb (U-5.5Nb) alloy, respectively. Applying ECAP, the U-5.5Nb alloy exhibited a single yield feature on the stress-strain curve in comparison to the “double yield” feature in the water quenched (WQ) counterpart. The difference is attributed to the characteristics of severe plastic deformation (SPD) structures obtained by ECAP. Mechanical machining resulted in a further severe microstructure refinement of the SPD surface layer with nano-grains/subgrains, which is accompanied with a dramatic increase of both the hardness and the elastic modulus of the surface layer. It is further proposed that the suppression of the shape memory effect (SME) in the nanostructured U-5.5Nb alloy may be responsible for the enhanced elastic modulus. The results of corrosion rate and pitting susceptibility showed a microstructure dependency, where the ECAP sample exhibited a better pitting resistance than that of the WQ counterpart.

采用等通道角挤压 (ECAP) 和机械加工分别将大塑性剪切应变引入 U-5.5wt.%Nb (U-5.5Nb) 合金的块体和表层。应用 ECAP，与水淬 (WQ) 对应物的“双屈服”特征相比，U-5.5Nb 合金在应力-应变曲线上表现出单一屈服特征。这种差异归因于 ECAP 获得的严重塑性变形 (SPD) 结构的特性。机械加工导致具有纳米晶粒/亚晶粒的 SPD 表面层的微观结构进一步细化，伴随着表面层硬度和弹性模量的急剧增加。进一步提出了抑制纳米结构 U-5 中的形状记忆效应 (SME)。5Nb 合金可能是提高弹性模量的原因。腐蚀速率和点蚀敏感性的结果显示出微观结构依赖性，其中 ECAP 样品表现出比 WQ 对应物更好的耐点蚀性。