Stress corrosion cracking of high entropy alloys: Mechanism, microstructure and performance

Stress corrosion cracking (SCC) presents a significant threat to structural components subjected to the synergistic combination of tensile stress and corrosive environments. While extensively studied in conventional alloys, the SCC behaviour of the emerging class of high-entropy alloys (HEAs) remains a frontier of research. This review synthesizes current knowledge to bridge this gap, systematically examining how the unique attributes of HEAs governed by their core effects of high entropy, severe lattice distortion, sluggish diffusion, and cocktail effect dictate their SCC response. The fundamental mechanisms of anodic dissolution and hydrogen embrittlement were analysed within the context of HEA's complex microstructures and compositional landscapes. Furthermore, the review critically assesses the influential roles of temperature and microstructural evolution on passive film stability and crack initiation. By integrating findings from key HEA systems, it is demonstrated that the core effects can be strategically leveraged to enhance SCC resistance by stabilizing protective films and impeding crack-propagation kinetics. However, this inherent complexity can also introduce vulnerabilities like micro-galvanic corrosion if improperly managed. This work concludes that a fundamental understanding of the interplay between electrochemistry, mechanics, and HEA thermodynamics is paramount for advancing the application of these materials in demanding environments like nuclear power, aerospace, and marine engineering.