Optimizing the strength and ductility of Cu–Al alloy by an ideal grain structure

Here an ideal grain structure, with short dislocation-slip path and low dislocation density, is fabricated in a Cu–Al alloy by combining equal channel angular pressing and cold rolling at liquid nitrogen temperature and subsequent annealing at 350 °C. The microstructure of this ideal structure is characterized by fine recrystallized grains in size of a few micrometers with abundant nanotwins and high angle grain boundaries. Accordingly, a good strength-ductility synergy combining a yield strength of 475 MPa and a uniform elongation of about 27.9% is obtained in tensile test. The transmission electron microscopy (TEM) examinations revealed effective hindering of dislocations by twin boundaries and storage of dislocations inside grains, which are responsible for the excellent strain hardening capability. This study provides a promising grain structure for industrial application.