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. 2023 Feb 27;123(5):2436–2608. doi: 10.1021/acs.chemrev.2c00799

Table 23. Research Opportunities on the Role of Scrap for Sustainable Aluminium Production (Green Aluminium).

Influence of scrap-related tramp elements in aluminum alloys on the thermodynamics and kinetics of precipitation reactions and their mechanical and electrochemical effects
Effect of scrap-related impurities on interface decohesion, phase formation, precipitation-free zones, precipitation kinetics, precipitation-free zones around grain boundaries, surface finish, mechanical properties and corrosion
Quality of thermodynamic and kinetic databases for the study of impurity-related spinodal, metastable and intermetallic phases
Influence of scrap-related contaminant elements on vacancy formation enthalpy and mobility
Inoculant systems suited for scrap-contaminated cast alloys
Scrap-related impurity effects on cast aluminum microstructures. Adjustment of solidification, solutionizing and heat treatment processes to cope with the effects of contaminant elements and the associated intermetallic phases
Possibilities of adjusting processing parameters for higher scrap tolerance such as higher cooling rates
Design and processing of aluminum alloys with the highest possible scrap fractions, using low-quality scrap and scrap types which match only a few target alloys when recycled
Improved and fully automated scrap sorting, including automated chipping, spectroscopy and artificial-intelligence-assisted alloy detection, classification and sorting
In-production scrap collection, including alloy-specific scrap collection during synthesis and manufacturing
Post-consumer scrap use along the development of low-grade and composition-tolerant alloys
Development of products that can tolerate and accommodate higher scrap-related contaminant content in alloys
Design of scrap-tolerant alloys for high-scrap-related tramp element content
Development of alloys that use less harmful and critical alloying elements
Selection of alloying elements according to lowest energy consumption and greenhouse gas emissions.
Avoidance of rare and less-responsible elements as alloying ingredients
Recycling as part of the entire alloy design workflow. This includes to ensure that alloys and by-products can be collected and recycled so that recyclability becomes an integral aspect of alloy and process design, considering also optimal material recovery of auxiliaries, scrap and unintended by-products
Closed scrap collection loops in-house and with customers
Methods for the removal of alloy-specific harmful tramp elements from scrap melts
Development of cross-over alloys and generally of alloys with higher impurity robustness to act as better scrap acceptor materials and more composition-friendly scrap donor materials