Production of Al7075 Alloy via Recycling of Al6063 and Zamak 5 Scraps: Chemical Composition Control and Liquid Metal Quality Assessment

Abstract

This study investigates a recycling-based melt development strategy for producing Al7075-type wrought feedstock melt chemistry from Al6063 extrusion scrap and Zamak 5 die casting scrap, with emphasis on melt cleanliness and compositional control rather than cast product development. An iterative alloy formulation approach supported by optical emission spectroscopy (OES) was employed to progressively adjust chemical composition, while liquid metal quality was evaluated using the reduced pressure test (RPT). Spatial chemical analysis demonstrated convergence toward Al7075-grade compositional targets, with impurity elements such as Si and Fe constrained primarily through charge selection under secondary processing conditions. RPT results showed moderately higher bifilm-related indicators and pore number density in the recycled melt relative to a laboratory remelted primary reference alloy; however, the differences remained limited in magnitude. Both melts exhibited lognormal pore size distribution behavior with broadly similar trends, indicating comparable but not equivalent defect population characteristics. The findings indicate that controlled recycling strategies can generate Al7075-grade melt chemistry with melt cleanliness approaching that of a primary reference condition under laboratory controlled processing.