Magnetic properties of bulk amorphous FeAlGaPCBSi samples prepared by ball-milling and subsequent hot pressing

Bulk amorphous FeAlGaPCBSi samples in the shape of discs (diameter of 10 mm and thickness of 3 mm) were prepared from melt-spun ribbons by high-energy ball milling and subsequent compaction of the resulting powder in the supercooled liquid region ΔTx. The stability against crystallization as well as the low viscosity in this region allow to prepare bulk specimens by combination of pressing and heating while the amorphous structure of samples is still maintained. Heating of the powder in the ΔTx region allows to reduce the stress induced in the material during ball-milling. This milling-induced stress causes significant differences in coercivity: the relatively low coercivity characteristic for the melt-spun ribbons (5–10 A m−1) increases after 1 h of ball milling to values of about 550–2300 A m−1. Subsequent heating of the ball-milled powders in the supercooled liquid region leads to a decrease of Hc to values between 9.5 and 250 A m−1. The bulk samples prepared by combination of compaction and heating (hot pressing) show a coercivity of about 11.6–127 A m−1.