Amorphization and ultrafine-scale recrystallization in shear bands formed in shock-consolidated Pr2Fe14B∕α-Fe nanocomposite magnets

Amorphization and ultrafine-scale recrystallization within shear bands formed in shock-consolidated Pr2Fe14B∕α-Fe nanocomposite magnetic powder compacts have been observed using transmission electron microscopy. The shear bands span through multiple grain lengths and truncate preexisting ∼25nm hard and soft magnetic phase grains, resulting in further grain size refinement. The shear bands contain nanocrystallites (<10nm size) interdispersed in an amorphous matrix, which suggests the occurrence of shock-induced phase transition in localized regions of the shear bands, and provides insight into the process of deformation of nanocrystalline materials under coupled high-strain-rate and high-pressure conditions.