The effect of annealing on magnetic properties, phase structure and evolution of free volumes in Pr-Fe-B-W metallic glasses

In the present work magnetic properties, phase structure and evolution of free volumes in the rapidly solidified Fe65Pr9B22W4 alloy ribbons in as-cast state and those subjected to short-time annealing were investigated. The base alloy was prepared by arc-melting of the high purity elements under an Ar atmosphere. The ribbon samples were obtained by melt-spinning technique under reduced pressure of Ar. As-cast samples were fully amorphous and have shown soft magnetic properties. In order to develop nanocrystalline microstructure, the specimens were annealed at temperatures ranging from 929 K to 1003 K for 5 min. Heat treatment caused the increase of volume fractions of hard magnetic phase, which was accompanied by significant changes of hysteresis loops. XRD studies revealed evolution of phase constitution of annealed ribbons. All annealed specimens contained hard magnetic Pr2Fe14B and paramagnetic Pr1+xFe4B4 phases. Positron annihilation lifetime spectroscopy (PALS) has been applied for detection of vacancy defects and positron-trapping voids. (C) 2016 Elsevier B.V. All rights reserved.