Positron Annihilation Spectroscopy for Heat-Treated Fe-Ga Alloys and Their Defect Structure

Abstract

We present the results of lifetime positron annihilation spectroscopy (PALS) for the ferrum–gallium alloys (galfenols) Fe–21at.%Ga and Fe–22.4at.%Ga, whose defect structure changes with annealing from 20 to 1000 $${^\circ }$$ C along the phase diagram of Fe $$_{100}$$ Ga $$_{100-x}$$ , at the L12 $$\,\rightarrow \,$$ A $$_{2}$$ transitions and in the sub-lattice of the D0 $$_{3}$$ phase. In frames of the standard trapping model, we estimate the positron annihilation parameters for the different thermal vacancies. Also we define concentrations of these vacancy defects, which may be helpful to provide an explanation of the physical properties of galfenols, including giant softening and extremal magnetostriction at the given intermetallic composition.