Method of producing Fe/Cr/Co permanent magnet alloy

A method of producing an anisotropic magnet alloy containing 17 to 45 weight % chromium, 5 to 35 weight % of cobalt and the balance being essentially of iron, in which a part of an aging treatment for making the alloy have a permanent magnetic property is conducted in a magnetic field to render the alloy anisotropical, which comprises effecting an aging treatment by at first maintaining said alloy in the magnetic field at a first temperature below the transformation temperature of said alloy at which two phases occur from a single phase, cooling the alloy at a rate of 0.05.degree. to 10.degree. C. per minute in the atmosphere, and then heating said alloy, while applying a magnetic field in the same direction, to a second temperature lower than the first temperature and below said transformation temperature, and maintaining said alloy under the magnetic field in the same direction at the second temperature, said aging treatment being conducted once or repeated two or more times.

A method of producing an anisotropic magnet alloy containing 17 to 45 weight % of chromium, 5 to 35 weight % of cobalt and the balance being essentially of iron in which a part of an aging treatment making the alloy have a permanent magnetic property is conducted in a magnetic field to render the alloy anisotropical, which comprises effecting an aging treatment by at first maintaining said alloy in the magnetic field at a first temperature below the transformation temperature of said alloy at which two phases occur from a single phase, cooling the alloy at a rate of 0.05.degree. to 10.degree. C. per minute and then maintaining said alloy under a magnetic field in the same direction at a second temperature lower than the first temperature and below said transformation temperature, said alloy being transferred from a first furnace in which the temperature is maintained at said first temperature to a second furnace in which the temperature is maintained at the second temperature.

A method of producing an anisotropic magnet alloy containing 17 to 45 weight % of chromium, 5 to 35 weight % of cobalt and the balance being essentially of iron in which a part of an aging treatment for making the alloy have a permanent magnet property is conducted in a magnetic field to render the alloy anisotropic, which comprises effecting an aging treatment by continuously cooling said alloy over a predetermined temperature range in said magnetic field, the cooling of said alloy in said magnetic field being commenced at a temperature higher than the transformation temperature of said alloy at which two phases occur from a single phase, and continued down to a temperature below said transformation temperature thereby to start the phase transformational reaction in said alloy during the continuous cooling to form the alloy having the permanent magnet property, said cooling being effected at a rate of 0.05.degree. to 10.degree. C. per minute.