The effect of grain size on the annealing-induced phase transformation in an Al0·3CoCrFeNi high entropy alloy

• Grain size affects annealing-induced phase transformations in Al0·3CoCrFeNi.
• Coarse-grained alloy transforms from FCC to L12 and finally to B2.
• Nanocrystalline alloy transforms from FCC directly to B2.
• Rapid elemental diffusion via grain boundaries in nanocrystalline alloy suppresses L12 formation.

The annealing-induced phase transformation was investigated in coarse-grained and severely deformed nanocrystalline face-centered cubic (FCC) high entropy alloys (HEA). Increasing temperature leads to phase transformations from the FCC phase to an L12 phase and finally to a B2 phase in the coarse-grained HEA. By contrast, direct transformation from the FCC phase to the B2 phase was observed in the nanocrystalline HEA at a lower temperature.

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