Abstract In this study, the uniaxial tension-tension fatigue behavior of fully nanotwinned magnetron sputtered Cu-6wt%Al, Cu-2wt%Al, and Cu-10 wt%Ni is presented. These alloys have average twin thicknesses ranging from 4 to 8 nm, average grain widths from 90 to 180 nm, and tensile strengths from 1 to 1.5 GPa. In the high cycle regime (103 to 107 cycles), the nanotwinned alloys exhibit fatigue strengths ranging from 210 to 370 MPa, which is higher than previously observed in nanotwinned Cu (fatigue strengths between 80 and 200 MPa). Fatigue strengths are normalized by tensile strength for Cu alloys with different microstructures to study the correlation between tensile and fatigue properties. Post-mortem analysis of the materials reveals a newly observed deformation mechanism, where localized detwinning leads to intergranular fracture between columnar grains. Overall, materials displaying detwinning as a deformation mechanism show lower normalized fatigue strengths in comparison to materials that deform with slip band like behavior.

中文翻译：

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疲劳纳米孪晶铜合金的显微组织变形

摘要 本研究介绍了全纳米孪晶磁控溅射Cu-6wt%Al、Cu-2wt%Al和Cu-10wt%Ni的单轴拉伸-拉伸疲劳行为。这些合金的平均孪晶厚度为 4 至 8 nm，平均晶粒宽度为 90 至 180 nm，抗拉强度为 1 至 1.5 GPa。在高循环状态（103 至 107 次循环）中，纳米孪晶合金的疲劳强度范围为 210 至 370 MPa，高于先前在纳米孪晶铜中观察到的疲劳强度（疲劳强度在 80 至 200 MPa 之间）。疲劳强度通过具有不同微观结构的铜合金的拉伸强度进行归一化，以研究拉伸和疲劳性能之间的相关性。对材料的验尸分析揭示了一种新观察到的变形机制，其中局部去孪晶导致柱状晶粒之间的晶间断裂。总体而言，与具有类似滑动带行为的材料相比，显示解缠作为变形机制的材料显示出较低的归一化疲劳强度。