Advancing Sustainable Aluminum Alloy Development via Comprehensive 3D Morphological and Compositional Characterization of Fe-Rich Intermetallic Particles

Abstract

With the push towards sustainable alloy production, using recycled material in casting Al alloys has become essential. However, high recycle content (HRC) aluminum alloys typically have a high iron content, leading to the formation of Fe-bearing intermetallic particles (Fe-IMCs) that affect the mechanical performance and formability of the alloy. Historically, 2D microscopy-based characterization techniques have been used to assess the size and morphology of these Fe-IMCs. While widely used, these 2D techniques are often incapable of capturing the complex 3D interconnected morphologies of the Fe-IMCs. In this work, we present a methodology for the high-throughput compositional and 3D morphological characterization of Fe-IMCs in a primary (AA 5182) and a high recycle content (HRC alloy) in the as-cast and homogenized states, using a combination of 3D X-ray Computed Tomography (XCT) and energy-dispersive X-ray spectroscopy (EDS). To capture the differences in morphology of the Fe-IMCs in the commercial and HRC alloys, we introduce a new 3D morphological descriptor—the particle-to-convex hull volume ratio (p/h). Finally, the effect of homogenization on the Fe-IMCs morphology was tracked using p/h, and a comprehensive analysis of the Fe-IMCs’ compositional and morphological evolution was presented.