Microstructural and magnetic behavior of nanocrystalline fe-12ni-16b-2si alloy synthesis and characterization

Abstract

The nanocrystalline Fe70Ni12B16Si2 (at.%) alloy was prepared by mechanical alloying (MA) of elemental powders in a high-energy planetary ball mill. Phase evolution, microstructure, thermal behavior and magnetic properties were investigated. It was found that a body-centered cubic structured solid solution started to form after 25 h milling and a faced-centered cubic structure solid solution started to form after 50 h of milling; its amount increased gradually with increasing milling time. The BCC and the FCC phases coexisted after 150 h of milling, with a refined microstructure of 13 nm and a 10 nm crystallite size. The as-milled powder was annealed at 450◦C and 650◦C and then investigated by vibrating sample magnetometry (VSM). It was shown that the semihard magnetic properties are affected by the phase transformation on annealing. The saturation magnetization decreases after annealing at 450◦C, whereas annealing at 650◦C improves the magnetic properties of 150 h milled powders through the reduction of coercivity from 109 Oe to 70 Oe and the increase in saturation magnetization.