Chemical fluctuation enabling strength-plasticity synergy in metastable single-phase high entropy alloy film with gigapascal yield strength

JY Zhang and QF He and J Li and Y Yang, INTERNATIONAL JOURNAL OF PLASTICITY, 139, 102951 (2021).

DOI: 10.1016/j.ijplas.2021.102951

In this work, we synthesized a FeCoNiCrCu high entropy alloy film (HEAF) via magnetron sputtering, which exhibited a metastable single FCC phase with random chemical distribution. Owing to the metastable nature, the as-deposited atomic structure affords nano-scale chemical fluctuation induced by moderate thermal annealing without causing phase transition. Compared to the single-phase FCC metals hitherto reported, our as- deposited and thermally annealed HEAFs exhibited the highest yield strength (3.4?4.2 GPa) under microcompression due to the combined action of nano-grains and growth twins. Furthermore, according to our experiments and atomistic simulations, plasticity-strength synergy was achieved as the nano-scale chemical fluctuation was able to promote deformation twinning in the HEAFs. The outcome of our research provides not only an atomistic understanding of the strength-plasticity synergy in the metastable FCC HEAFs with gigapascal yield strength, but also a facile method to design high performance metastable chemically complex metallic films.

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