Recycling-driven processing pathways for high entropy alloys: Towards sustainable materials design and manufacturing

The growing demand for critical metals, coupled with the environmental impacts of primary extraction, has accelerated interest in recycling-based synthesis of high-entropy alloys (HEAs/MPEAs), a transformative materials class defined by multiple principal elements and high configurational entropy. This review consolidates recent advances in the fabrication, impurity tolerance, and recyclability of HEAs/MPEAs derived from secondary or waste feedstocks, emphasizing sustainable metallurgical design strategies. Particular attention is given to thermodynamic and kinetic factors governing impurity incorporation, recovery efficiency, and property retention during powder metallurgy, additive manufacturing, and spark plasma sintering processes. Quantitative frameworks such as the combinatorial methods (C IM ) and material compatibility classification models are integrated to explain how elemental interactions influence alloy recyclability and mechanical integrity. The review highlights that transition-metal-based HEAs (Fe-, Ni-, and Co-rich systems) demonstrate superior chemical tolerance and recoverability compared to low-melting or volatile systems (Pb-, Sn-, and Si-containing alloys). Furthermore, emerging digital design and life-cycle assessment tools are identified as major enablers for circular HEA production. By synthesizing thermodynamic insights, process compatibility, and sustainability metrics, this review establishes a data-driven foundation for designing recyclable, impurity-tolerant HEAs, offering new pathways toward decarbonized, resource-efficient alloy manufacturing.