Fabrication and soft-magnetic properties of Fe–B–Nb–Y glassy powder compacts by spark plasma sintering technique

Magnetic properties of (Fe_0.72B_0.24Nb_0.04)_95.5Y_4.5 sample were investigated. The sample was produced from glassy powders made by the gas-atomization and consolidation using the spark plasma sintering (SPS) technique. Maximum relative density of 99.5% was achieved in the spark plasma sintered (SPSed) compact due to the viscous flow enhanced by the applied stress even under the glass transition temperature. X-ray diffraction pattern of the compact indicates that the glassy structure was maintained through the SPS process. However, the results of differential scanning calorimetry (DSC) showed that the glass transition temperature and crystallization temperature of the SPSed glassy compact shift to a higher and lower temperature, respectively, that is, a smaller ΔT_x. Saturation magnetization of the SPSed glassy compact became 10% higher than that of the initial glassy powder. The Curie point was enhanced from 522 K for the glassy powder to 548 K for the SPSed glassy compact. Spin-exchange interaction is expected to be enhanced by a short-range scale atomic rearrangement caused by the high applied stress and temperature during the SPS process.