Akademik Veri Yönetim Sistemi
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, cilt.128, sa.8, 2022 (SCI-Expanded)
In this study, four different equimolar compositions of FeCoNi, FeCoNiNb, FeCoNiCr, and FeCoNiNbCr were synthesized by the mechanical alloying method. The effects of Cr and Nb addition on the structural, morphological, and magnetic properties of FeCoNi alloy were investigated in detail. The structural aspects of the samples were analyzed by X-ray diffractometer and scanning electron microscope equipped with an energy dispersive X-ray spectrometer. High and low-temperature magnetic properties were evaluated by a vibrating sample magnetometer. It was noticed that the addition of Nb caused amorphization, while Cr promoted crystallization in the alloys. The crystallite sizes were calculated as 9.7, 3.1, 8.3, and 4.4 nm for the FeCoNi, FeCoNiNb, FeCoNiCr, and FeCoNiCrNb alloys, respectively, after 20 h of milling. The SEM images of the as-milled alloys revealed irregular and layered structures for FeCoNi and FeCoNiCr alloys of mean particle sizes around 140 and 120 mu m. In contrast, the addition of Nb in these alloys, viz. FeCoNiNb and FeCoNiNbCr alloys, formed mostly spherical with irregular morphologies of particle sizes ranging between 55 and 80 mu m. It was noticed that the low solubility of Cr caused precipitation at the grain boundaries of the alloy particles, and it contributed to the formation of hard structures of irregular and layered morphologies. The observed increase in the lattice parameters and lattice strain in the solid solution phases of all-alloy systems studied was mainly due to the lattice distortion and intense plastic deformations. The maximum saturation magnetization obtained from the room temperature hysteresis loops was 150.4 emu/g for the FeCoNi alloy after 10 h of milling. The additions of non-magnetic Cr, Nb, and both into FeCoNi, caused a significant decrease in the saturation magnetization. The coercivity of the as-milled alloys was also found to decrease with the reduction in the nano-crystallite sizes, which elucidated that the crystallite sizes of the alloys were smaller than the magnetic exchange length. The high-temperature magnetization curves revealed that all alloys studied had Curie temperature higher than 700 K.