Enhanced strength-ductility combination in the aluminum-gold system by heterogeneous distribution of nanoparticles via ultra-severe plastic deformation and reactive interdiffusion.

• Heterogeneous nanoparticle distribution is introduced to improve strength-ductility synergy. • A model Al-Au alloy is selected to examine the efficiency of this new strategy. • The use of ultra-severe plastic deformation leads to the Al 2 Au nanoparticle formation. • Heterogenous Al 2 Au distribution improves both strength and ductility. • Ductility is lost when nanoparticle distribution becomes uniform. Ultrafine-grained aluminum alloys are of interest due to their high strength-to-weight ratio, but they usually suffer from poor uniform ductility. In this study, an Al-Au alloy with a good combination of strength and ductility is produced by the heterogeneous distribution of Al 2 Au nanoparticles in an aluminum matrix. To generate such heterogeneity, the alloy is synthesized by ultra-severe plastic deformation of aluminum and gold powders via the high-pressure torsion (HPT) method. Reactive interdiffusion occurs during the process leading to the heterogeneous formation of intermetallic particles and a good strength-ductility synergy (200 MPa yield stress and 15% uniform elongation). Nanoparticles gradually distribute within the matrix and once a uniform nanoparticle distribution is achieved, the alloy shows no further increase in strength, but it completely loses its ductility. It is concluded that not only the presence of nanoparticles but more importantly the heterogeneity of their distribution can positively influence the strength-ductility combination in ultrafine-grained aluminum alloys. The findings of this study suggest that future studies on heterogeneous precipitation hardening can be a solution to achieve ductile precipitation-hardened alloys. [Display omitted] [ABSTRACT FROM AUTHOR]