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

• Published in: Journal of alloys and compounds 2017-02, Vol.694, p.228-234
• Main Authors: Filipecka, K., Pawlik, P., Filipecki, J.
• Format: Article
• Language: English
• Subjects: Amorphous materials; Annealing; Constitution; Diffraction; Electric arc melting; Evolution; Heat treating; Heat treatment; Hysteresis loops; Iron; Lattice vacancies; Magnetic properties; Melt spinning; Metallic glasses; Microstructure; Mössbauer spectroscopy; Nanocrystals; Permanent magnets; Positron annihilation; Positron annihilation lifetime spectroscopy; Rapid solidification; Ribbons; Rietveld analysis; Solid phases; Solidification; Tapes (metallic); X-ray diffraction
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2016.09.321

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. [Display omitted] •Annealing of Fe65Pr9B22W4 alloy ribbons results in changes of magnetic properties.•Heat treatment causes the formation of hard magnetic and paramagnetic phases.•For the short-time annealed samples the dominant is paramagnetic Pr1+xFe4B4 phase.•Crystallite sizes and unit cell parameters changes with annealing temperatures.•Coercivity increase with the increase in size of defects present in the samples.