New Bayesian-Optimization-Based Design of High-Strength 7xxx-Series Alloys from Recycled Aluminum

Over the next decade, a large number of airplanes will reach the end of their useful life, providing an obvious source of valuable used metals such as 7075 alloy. In this project, old 7075 was remelted and alloyed with pure alloying elements to create new 7xxx-series alloys with enhanced performance. Aerospace alloys are extremely complex with multiple alloying elements and numerous processing steps, often making their optimization labor intensive and costly. In the current study, Bayesian optimization was used as the basis for adaptive experimental optimization to explore and optimize this multivariable problem. Novel Al alloys, based on the 7075 alloy, were proposed and their heat treatment processes optimized. Exhibiting maximum yield strength and ultimate tensile strength of 729 MPa and 761 MPa, respectively, the mechanical properties of the newly designed alloys are comparable to or exceed those of the current generation of high-strength 7xxx-series Al alloys.