Solving the strength-ductility trade-off using complex concentrated alloy design strategy: An overview

This review provides a comprehensive assessment of recent advances in overcoming strength–ductility trade-off in structural alloys through the design of complex concentrated alloys (CCAs) and high entropy alloys (HEAs). It integrates a bibliometric analysis (2014–2024) with a mechanistic evaluation of emerging strategies, emphasizing transition metal-based systems. Findings from over 2,200 publications highlight growing global collaboration, dominant research clusters, and underexplored domains such as TRIP/TWIP effects and interstitial strengthening. Mechanistically, the review consolidates insights into solid solution, grain boundary, dislocation, precipitation, and interstitial strengthening; together with advanced mechanisms including stacking fault engineering, phase metastability, and heterostructural design. Emphasis is placed on the synergistic operation of these mechanisms especially TWIP/TRIP and back-stress hardening, to achieve superior strength–ductility combinations. Distinctions between HEAs and CCAs are clarified, and quantitative contributions of each strengthening mechanism are mapped. The role of hydrogen effects, additive manufacturing, and multi-scale processing in tailoring properties are discussed. By synthesizing bibliometric trends and mechanistic principles, this review establishes a roadmap for future alloy design strategies, offering a robust framework to guide the development of next-generation structural materials with multifunctional performance attributes.