High-cycle fatigue behavior and life prediction of coherent precipitate-strengthened multi-principal element alloys

Coherent precipitate-strengthened multi-principal element alloys (CPS-MPEAs) exhibit exceptional mechanical properties, making them promising candidates for structural materials. However, their fatigue performance, a crucial factor for practical applications, remains largely unexplored. This study investigates the fatigue behavior of a CoNiCrAlTi CPS-MPEA, revealing significantly improved fatigue strength compared to MPEAs with no coherent precipitates (NCPS-MPEA). This improvement is related to the formation of shear bands, which contrast with the stress-concentrating dislocation cells typically observed in NCPS-MPEA. Consequently, the shear bands delay the initiation of cracks and reduce crack propagation velocity. To predict fatigue life of CPS-MPEA, we establish the first comprehensive fatigue database incorporating critical mechanistic descriptors, with machine learning (ML) serving as a validation tool. Key factors governing fatigue resistance, such as precipitate volume fraction, are identified, and optimal parameters are suggested. This work deepens our understanding of fatigue resistance in CPS-MPEAs and provides valuable guidance for designing high-performance MPEAs.