Static recrystallization of shock-wave (explosively) deformed Fe–40 at% Al–Zr–B intermetallic

Abstract

A B2 Fe–40 at% Al–Zr–B iron aluminide was subjected to shock-wave (explosive) loading at ∼6 GPa shock pressure. The applied shock pressure was sufficient to generate high dislocation density in the material which, in turn, gave rise to primary static recrystallization process upon subsequent isothermal annealing at 700, 750 and 800°C for various lengths of time. At various annealing temperatures recrystallization occurs rather inhomogeneously. Nucleation occurs mostly at the triple points and grain boundaries, showing tendency for clustering. Recrystallization kinetics follows a general behavior according to the Johnson, Mehl, Avrami and Kolmogorov theory (JMAK) with the Avrami exponent, n∼2.3–2.9. The estimated apparent activation energy for recrystallization, ∼259 kJ/mol, is very close to the activation energy for self-diffusion in pure iron and iron in FeAl. The results of microhardness studies of partially recrystallized specimens indicate that the average Vickers microhardness values for recrystallized and unrecrystallized areas differ significantly, the former having higher microhardness. This phenomenon is discussed in terms of higher density of retained sinks for quenched-in vacancies in the unrecrystallized areas and lower efficiency of vacancy hardening.