Fe-Cr-Co Permanent magnet alloy and alloy processing

Claim 1

Method for producing a magnetic element comprising a body of an alloy consisting of 25-29 weight percent Cr, 7-12 weight percent Co, and remainder Fe CHARACTERIZED IN THAT said method comprises the steps of (1) subjecting said body to an annealing temperature which is such that, (a) said annealing temperature is greater than or equal to 650 degrees C., (b) said annealing temperature is less than or equal to a temperature which is obtained by approximate linear interpolation between a temperature of 950 degrees C. corresponding to an alloy comprising 25 weight percent Cr and 7 weight percent Co, a temperature of 875 degrees C. corresponding to an alloy comprising 25 weight percent Cr and 12 weight percent Co, a temperature of 1100 degrees C. corresponding to an alloy comprising 29 weight percent Cr and 7 weight percent Co and a temperature of 975 degrees C. corresponding to an alloy comprising 29 weight percent Cr and 12 weight percent Co, (c) said annealing temperature is less than or equal to 1000 degrees C. whereby an average grain size not exceeding 70 micrometers is obtained in said alloy, (2) forming said body into a desired shape at a temperature not exceeding 100 degrees C. either by wire drawing or deep drawing by an amount corresponding to a cross-sectional area reduction of at least 50 percent or by deep drawing or bending so as to result in a change of direction of at least 30 degrees, the resulting radius of curvature being such that it does not exceed a value which is proportional to change in direction, which for a 30 degree change in direction is equal to the thickness of the part being bent, and which for a 90 degree change of direction is equal to 4 times the thickness of the part being bent, and (3) aging said alloy.