Abstract
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 Al2Au nanoparticles in an alu-minum matrix.To generate such heterogeneity,the alloy is synthesized by ultra-severe plastic deforma-tion 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 pres-ence of nanoparticles but more importantly the heterogeneity of their distribution can positively influ-ence 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.
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