Preparation and soft magnetic properties of spark plasma sintered compacts based on Fe–Si–B glassy powder

Abstract

Amorphous powder of Fe75Si20B5 (at.%) was prepared by wet mechanical alloying route using benzene as surfactant. The amorphous phase is obtained after 60h of milling. Structural, morphological, and thermal characteristics were investigated. The as-milled powder consists in micrometric particles with a mean diameter of 10.4μm which are formed by the agglomeration of smaller particles. The amorphous powder is thermally stable up to the temperature of 490°C. Spark plasma sintered compacts were prepared from the amorphous powders at sintering temperatures of 800, 850 and 900°C. The phases formation and their evolution was investigated by X-ray diffraction technique showing that Fe3Si and Fe2B are the main phases formed during the spark plasma sintering process. Fe75Si20B5 (at.%) samples in the form of a ring were investigated in DC and AC magnetization regime. It was found that the boride phase formation (during sintering) and the low density of the compacts affect the magnetic properties of the compacts. In addition, a superficial contamination of the compacts with carbon (a layer of 2–3μm) was evidenced, contributing thus to their soft magnetic deterioration. Increasing of the saturation induction, maximum relative permeability and initial relative permeability was observed by increasing both sintering temperature and time. It was generally observed that the compacts with high density have higher total core losses at high frequency.