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/alpha-Fe nanocomposite magnetic powder compacts have been observed using transmission electron microscopy. The shear bands span through multiple grain lengths and truncate preexisting similar to25 nm hard and soft magnetic phase grains, resulting in further grain size refinement. The shear bands contain nanocrystallites (<10 nm 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. (C) 2004 American Institute of Physics.