Effect of the Boron Content on the Amorphization Process and Magnetic Properties of the Mechanically Alloyed Fe92−xNb8Bx Powders

Abstract

The effect of the B content on the microstructural, structural, and magnetic properties of partially amorphous Fe92−xNb8Bx (x = 5, 10, 15, and 20) alloys has been investigated by means of scanning electron microscopy, X-ray diffraction, high and low-temperature extraction-type magnetometers. The XRD results reveal the formation of a nanocomposite structure where nanocrystalline bcc α-Fe and Fe2B phases are embedded into an amorphous matrix. The FeB boride is observed for higher boron contents (x = 15 and 20), and the crystallite sizes are in the range of 7–24 nm. As the B content increases, the amorphous phase-relative proportion and coercivity increase, whereas the saturation magnetization decreases. An important magnetic hardening occurs by lowering the temperature from 400 to 5 K for x = 20% B. The variation of the Curie temperature can be attributed to the heterogeneity of the amorphous matrix

This work has been supported by the Algerian Ministère de l’Enseignement Supérieur et de la Recherche Scientifique, the PHC-Maghreb 15 MAG07 program and the Spanish MINECO projects MAT2013-47231-C2-2-P and MAT2016-75967-P