Achieving strength-ductility synergy by tailoring the domain size of ultrafine structures in heterostructured Cu

The improvement of strength in the heterostructures consisting of ultrafine structures and coarse grains is generally achieved by tailoring the volume fraction of ultrafine structures, but this comes at the expense of ductility. In this work, we succeeded in maintaining the volume fraction of ultrafine structures in heterostructured Cu while tailoring their domain sizes. Interestingly, reducing the domain size of the ultrafine structures from -38 mu m to -20 mu m increases the yield strength of the heterostructured Cu by -40% without sacrificing any uniform elongation. The synergy of strength and ductility results from the additional heterointerfaces induced by smaller domains, which could accumulate more geometrically necessary dislocations to provide extra strength.