Capacitor Electrical Discharge Sintering of Amorphous Fe-Si-B Powder

Abstract

High purity powders of Fe, Si and B mixed with atomic composition Fe78Si9B13 are subjected, after arc melting, to a melt spinning process. The amorphous ribbons are transformed into powder by mechanical milling, reaching mean sizes of 65 and 262 µm, taking care of maintaining the amorphous character. The powders are sintered by means of a very quick capacitor electrical discharge (CEDS), while trying to maintain the initial structure of the powders. The CEDS process is analyzed depending on the thermal energy applied during the discharge, as well as on the particle size of the powders and the powders’ mass. The porosity, microstructure, hardness, electrical resistivity and magnetic properties of the prepared compacts are analyzed. Thus, for powders with a mean size of 262 μm, the porosity can be reduced from 0.33 to 0.11 after sintering, reaching a microhardness of up to 1100 HV1 after applying a discharge of 2640 J/s. A coercivity of 1895 A/m and a saturation flux density of 1.32 T are achieved in the compact, which maintains a microstructure with up to 64% of amorphous phase.