Process for the thermal treatment of Fe-Co-Cr alloys for permanent magnets

摘要

A process for the thermal treatment of an Fe-Co-Cr alloy for a permanent magnet, constituted by weight of 10 to 40% of Cr, from 0 to 10% of one or more elements of the group Al, Nb, Ta, W, Mo, V, Ti, Si and Cu, the remainder being iron. The process comprises homogenization treatment at between 1200° and 1400° C., an annealing treatment and one or more tempering treatments at between 500° and 600° C. ; the annealing treatment comprises two stages, the first at between 630. degree. and 670° for 5 to 30 minutes, the second, without a return to ambient temperature, at a temperature of from 40° to 70° C. below the previous stage for at least 10 minutes.PP Isotropic or anisotropic magnets whose hysteresis curve exhibits a better rectangular shape are thus obtained.