Recrystallization and grain growth activation energies in a hybrid magnesium material fabricated by high-pressure torsion.

• E a of recrystallization of hybrid AZ31/Mg-0.6Gd was estimated as 112 ± 10 kJ/mol. • Mg 17 Al 12 and Mg 2 Zn phases in the AZ31 region obstructs the grain growth process. • The effect of Mg 5 Gd and Mg 12 Gd phases in the mg-0.6gd region is less evident. The recrystallization and grain growth activation energies of the hybrid AZ31/Mg-0.6Gd (wt.%) alloy were calculated using differential scanning calorimetry analyses and scanning electron microscopy, respectively, after fabricating by high-pressure torsion up to 20 turns and then subjecting to an isochronal annealing treatment from 423 to 723 K for 1 h. The DSC results show one exothermic peak belonging to the static recrystallization of the AZ31 region with an activation energy of 112 ± 10 kJ/mol. The grain growth kinetics for the AZ31 and Mg-0.6Gd regions were described by the Arrhenius equation. The calculation with a grain growth exponent equal to 4 gave values for the activation energies in both the AZ31 (146.2 ± 8.4 kJ/mol) and Mg-0.6Gd (90.9 ± 13.5 kJ/mol) regions. The present results reveal the heterogeneity of the thermal stability of the AZ31/Mg-0.6Gd hybrid material. [Display omitted] [ABSTRACT FROM AUTHOR]