Precipitation hardened RE--Co-magnets

Magnetic and metallographic investigations are reported on Sm(Co,Cu)/sub z/ with 5 less than or equal to z less than 8.5 and Cu-contents up to 35 percent of the transition metal fraction. The as-cast as well as the heat treated materials were evaluated. Two typical compositions Sm(Co/sub 0/./sub 65/Cu/sub 0/./sub 35/)/sub 5/./sub 6/ as an example of a single phase 1:5 type magnet material and Sm(Co/sub 0/./sub 84/Cu/sub 0/./sub 16/)/sub 6/./sub 9/ as an example of a two phase magnet material, namely a primary 2:17 phase in a 1:5 type matrix, are considered in detail. Both materials produced, after an appropriate high temperature annealing, rectangular ideal demagnetization curves, implying that the macroscopic 2:17 primary phase is magnetically hard. Low temperature heat treatments resulted in two maxima in the coercivity /sub I/H/sub C/ as a function of T. The data are discussed based on metallurgical investigations of the phase diagrams and electron microscopy results.