Unusual behavior of long-range order parameter in Fe3Al superstructure under severe plastic deformation in Bridgman anvils

Abstract

By X-Ray diffraction and transmission electron microscopy methods the evolution of long-range order parameters and morphology of antiphase boundaries in Fe3Al superstructure (DO3 type) under high pressure torsion (HPT) in Bridgman anvils at room temperature have been investigated. It was detected a new phenomenon: the partial restoration at the N ≥ 1 of completely destroyed D03 long-range order under the HPT deformation (N - the number of complete revolutions of the movable anvil). It was shown that the discovered effect is due to the activation of low-temperature dynamic recrystallization under the SPD and, as a result, to occurrence of the mixture of deformation fragments and recrystallized grains. The averaged long-range order parameter for the first coordination sphere is equal to 0.24–0.26 at N ≥ 2. It was estimated that the value of restored parameter of ordering inside the recrystallized grains is approaching the initial one at the N = 2 and corresponds to the partial restoring at the N > 2.