A novel hard magnetic material for sintering permanent magnets

We have discovered that the substitution of Ga or Si for Fe in Sm2Fe17Cx helps the formation of high-carbon rare-earth iron compounds with 2:17-type structure. We have succeeded in preparing Sm2Fe15M2Cx (M=Ga, x=0, 1.0, 2.0, and 3.0; M=Si, x=0, 0.5, 1.0, and 1.5) compounds with Th2Zn17-type structure by arc melting. The carbides are single phase except for Sm2Fe15Ga2C3.0, which contains a few percent of α-Fe. The Curie temperature TC of Sm2Fe15Si2Cx compounds is found to increase from 550 to 590 K, as x increases from 0 to 1.5. For Sm2Fe15Ga2Cx, TC increases with x from 565 K for x=0 to 635 K for x=2.0, and then decreases with x. Room-temperature saturation magnetization of these carbides is in excess of 100 emu/g and has a small dependence on carbon content. All compounds of Sm2Fe15M2Cx studied in this work except for Sm2Fe15Si2 exhibit an easy c-axis anisotropy at room temperature and show an anisotropy field of higher than 90 kOe for x≥1.0. The present work suggests the possibility of producing high-performance 2:17-type sintering permanent magnets.