This paper describes magnetic and metallographic properties of rare-earth-cobalt alloys of (Sm, Ce) (Co, Fe, Cu)
z(

). Some alloy compositions exhibit anomalously large coercive forces and have excellent potential for permanent-magnet application. The composition Sm
0.75Ce
0.25(Co
0.81Fe
0.04Cu
0.15)
7.2shows a maximum energy product of 20.2 MG Oe, which is the highest among the compositions studied. Most alloys exist in the CaCu
5-type crystal structure although some show a few of very weak superlattice lines characteristic of hexagonal Th
2Ni
17. When aged at about 960°C, the alloys show another phase in addition to the aforementioned structures.