Improved Fatigue Strengths of Nanocrystalline Cu and Cu-Al Alloys

Increasing the fatigue strengths of high-strength materials, especially their endurance limits is essentially challenging. The fatigue strengths of nanocrystalline (NC) Cu and Cu-Al alloys processed by high-pressure torsion were prominently enhanced with a decrease in stacking fault energy. This remarkable escalation can be attributed not only to their significantly increased tensile strengths in macro-scale, but also to the essentially improved microstructure stability and reduced strain localization within shear bands in microscale. Owing to the limitation of their intrinsic fatigue mechanisms, the fatigue limits of NC Cu and Cu-Al alloys cannot always acquire appreciable improvement with their monotonic strengths.