Superior fatigue crack growth resistance in bulk Cu with highly oriented nanotwins

We studied the fatigue crack growth (FCG) characteristics of bulk nanotwinned Cu (NT-Cu) with different microstructural aspects such as grain size and twin thickness. We specifically addressed the crack closure, with particular emphasis on the intrinsic FCG resistances in the near-threshold regime. The results demonstrate that the NT-Cu samples have significantly improved fatigue resistances compared with conventional twin-free polycrystalline Cu, a fact we measured using the effective threshold stress intensity factor range, Delta Kth,eff. This enhanced resistance can be traced back to the activation of a specific set of primary slip systems in the NT-Cu, known as special trans-twin dislocation, which dominates the crack-tip cyclic deformation, leading to a diminished level of cyclical slip irreversibility and, in turn, enhancing the inherent resistance to damage propagation.

Automated summary

In this study, we investigated the fatigue crack growth characteristics of bulk nanotwinned Cu with different microstructural aspects. The results show that the nanotwinned Cu has significantly improved fatigue resistance compared to conventional polycrystalline Cu, which can be attributed to the activation of specific primary slip systems.