Iron-chromium-cobalt sintered magnet alloy - with good hot and cold workability

摘要

Sintered magnet alloy comprises 20-35% Cr, 3-15% Co and the balance Fe and impurities. Alloy has theoretical density at least 97% and magnetisability at least (BH)m5.OMGO. Prepn. comprises (a) compressing a powdery mixt. of sigma and Fe grains of size 200 meshes or less and (b) sintering at a temp. of 1250-1450 deg.C in a non-oxidising atmos. or in vacuo. The powdery mixt. may be a combination of carbonyl Fe with Fe-Cr or sigma grains. Alloy has good hot and cold workability. The sigma phase grains, which exist in a wide Cr range around 45% Cr of Fe-Cr or Fe-Cr-Co alloys, can be easily mechanically crushed to fine grains without substantial oxidn. Sintered article having high density can be produced without the need for any special additives. Prod. shows good workability, compressability and fluidity, when the powdery mixt. contains Co.