Recycling-oriented alloy design for next-generation of sustainable metallic materials

Call: HORIZON-MSCA-2021-PF-01 (MSCA Postdoctoral Fellowships 2021)

Keywords: metals; alloys; green metallurgy; recycling; green deal; microstructure; structure-property; mechanical testing; fracture toughness; in-situ testing, toughness, ductility, damage-tolerance

Abstract: European industry increasingly focusses on recycling, pushing towards circular economy as part of EU Green deal. This offers enormous energy savings and CO2 reductions. However, there are several problems hindering the metals recycling. Effective solution to counter these problems is the development of new alloys, recycling-friendly by design. One of the rising problems during recycling, is the progressive accumulation of impurities in alloys produced from scrap metal. Elements such as tin cannot be effectively removed during manufacturing alloys from scrap. Therefore, the next generation of alloys will have be able to tolerate more impurities (therefore inclusions) than current alloys. Such materials also have to be more resistant to fracture, due to the potential damage nucleation at inclusions. However, impurities cause significant changes of properties and induce considerable complexity even in simple alloy systems. Therefore, the development of the recycling-oriented alloys based on understanding of changes caused by various compositional deviations require a significant volume of research. Concentrated solid solution alloys, including some of the established compositions of austenitic steels have the attributes essential for recycling-oriented alloys. They show enhanced tolerance to compositional deviations due to the extended compositional space with desired microstructures. and intrinsically high ductility levels.

In this project, we first aim to analyze the consequences of the compositional changes and impurities to the changes of mechanical properties and damage-tolerance of said materials. Ultimately, scrap-compatible alloys for sustainable metallurgy will be prepared. Special attention will be placed on the effects of the elemental partitioning and their interactions with defects. The project outcomes will contribute to the development of recycling-oriented alloys on the global level, for future green metallurgy with reduced environmental impact.

Fig. 1: The life-cycle of metallic products including the raw materials used in manufacturing. The new metals are manufactured either from primary sources (ores) or from already used recycled materials (scrap metal). The increase in volume of new metals produced from remelted scrap is, and will be rising in the future. Higher utilization of scrap leads to a closed recycling loops enabling higher energy efficiency and significant CO2 reductions as a par of transformation to circular economy. However, the future alloy compositions have to be adjusted to reflect the peculiarities connected to the change of the source materials, such as for instance increase in the concentration of residual, tramp elements that cannot be effectively removed from new materials.