Discovery of aluminum alloys with ultra-strength and high-toughness via a property-oriented design strategy

Aluminum alloys with ultra-strength and high-toughness are fundamental structural materials applied in the aerospace industry. Due to the intrinsic restriction between strength and toughness, optimizing a desirable combination of these conflicting properties is always challenging in material development. In this study, 171 sets of data were curated based on the characteristics of high-strength and high-toughness aluminum alloys in the literature. Then, a machine learning design system (MLDS) with a property-oriented design strategy was established to rapidly discover novel aluminum alloys with ductility and toughness indexes (with elongation 8= 8%-10% and fracture toughness K IC = 33-35 MPa middotm 1/2 ) comparable to those of current state-of-the-art AA7136 aluminum alloys when the ultimate tensile strength (UTS) exceeded approximately 100 MPa, with values reaching 700-750 MPa. With the MLDS for experimental verification, three typical candidate alloys show satisfactory performance with UTS of 707-736 MPa, 8 of 7.8%-9.5%, and K IC of 32.2-33.9 MPa middotm 1/2 . The high contents of Mg and Zn alloying elements in the novel alloys form abundant eta' phases, which produce a significant hardening effect, while the reasonable matching of Cr, Mn, Ti and Zr dispersoids refines the grain size. The decreased Cu content compared with that in the AA7136 alloy inhibits the formation of the Sigma phase and S phase, so that the alloys show high toughness. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

Aluminum alloys with ultra-strength and high-toughness are essential materials in the aerospace industry, but balancing these properties is challenging. This study used a machine learning design system to discover novel aluminum alloys with comparable properties to current state-of-the-art AA7136 alloy. The new alloys have high Mg and Zn content for hardening and refined grain size due to dispersoids.