Composition-dependent apparent activation-energy and sluggish grain-growth in high entropy alloys


Experimental results reveal that the apparent activation-energy for grain-growth in an fcc-based AlxCoCrFeNi high entropy alloy (HEA) system increases from 179 to 486kJ/mol when the Al content increases from x=0.1 to 0.3. These unexpectedly high apparent activation-energy values can be potentially attributed to solute clustering within the fcc solid-solution phase that develops with increasing Al content in this HEA. Detailed microstructural analysis using atom-probe tomography and density functional theory (DFT) calculations strongly indicate the presence of such nanoscale clusters. This phenomenon can change grain-growth from a classical solute-drag regime to a much more sluggish cluster-drag based mechanism in these HEAs. [GRAPHICS] IMPACT STATEMENTFirst report on a composition dependent change in apparent activation-energy for grain-growth in high entropy alloys. A novel cluster drag effect inhibiting grain-growth kinetics is suggested.

High entropy alloy, grain-growth, activation-energy, atom-Probe tomography, HALL-PETCH, BOUNDARY MOTION, STRENGTH, DRAG, Materials Science, Multidisciplinary, Materials Science
Gwalani, B., Salloom, R., Alam, T., Valentin, S., Zhou, X., Thompson, G., Srinivasan, S., Banerjee, R. (2019): Composition-Dependent Apparent Activation-Energy and Sluggish Grain-Growth in High Entropy Alloys. Materials Research Letters. 7(7).