Experimental and Computational Study of Microstructure of Al₂FeCoNiCu High-Entropy Alloy

MB Kivy and AK Mahata and R Thompson and J Palominos and M Kestenbaum and L Hunter, JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION, 44, 76-85 (2023).

DOI: 10.1007/s11669-023-01024-4

Microstructure and phase equilibria of Al2FeCoNiCu high-entropy alloy were investigated by a combination of experiments and multiscale computational materials. The CALPHAD and experimental results showed that a BCC dendritic phase formed during solidification, while a Cu-rich inter-dendritic phase with FCC structure precipitated at lower temperature. These FCC inter-dendritic phases were also surrounded by acicular precipitates with the same structure and composition. These acicular precipitates were stable during homogenization of the alloy at 550 degrees C, but they started to dissolve when heat-treated at 900 degrees C. Molecular simulation results revealed a disparate mechanism between nucleation of the FCC phase and its growth. While low annealing temperature (large undercooling of BCC) aided the nucleation process, diffusion-driven growth of the FCC crystals was faster at higher annealing temperatures.

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