Annealing-induced crystallization of the Er^sub 2^Fe^sub 13.8^B alloy amorphized by irradiation

To study the evolution of structural and magnetic states of irradiation-amorphized Er^sub 2^Fe^sub 13.8^B alloy during isothermal annealing at temperatures of 295-1025 K, magnetization measurements and neutron diffraction analysis have been performed. The annealing of the alloy leads to the crystallization of the Nd^sub 2^Fe^sub 14^B-type phase, the amount of which reaches about 84% of the sample volume, and [alpha] Fe (16%). Neutron diffraction studies have shown that the Er^sub 2^Fe^sub 13.8^B alloy crystallizes in a temperature range of 590-638 K. Magnetic measurements indicate the increase in the spontaneous magnetization and coercive force as the annealing temperature increases above 800 K. The magnetization of the Er sublattice in the sample annealed at 993 K is lower than that of the crystalline sample before its amorphization. However, the magnetic anisotropy of the Er sublattice is unchanged, i.e., the easy axes remain oriented in the basal plane of the tetragonal lattice.