High coercivity of melt–spun Sm2Fe15Al2C1.5 compound

The magnetic hardening of melt–spun Sm2Fe17Cx was studied and the coercivity of 4.6 kOe for Sm2Fe17C1.5 alloys was reported a few years ago. Recently, we have succeeded in preparing single-phase compounds of Sm2(Fe, M)17Cx (M=Ga, Al, or Si) with high carbon concentration by arc melting. It was found that the substitution of Ga or Al not only facilitated the formation of high carbon concentration rare-earth iron compounds with a 2:17-type structure, but also was very effective in raising the value of the anisotropy field. For example, the sample of Sm2Fe15Al2C1.5 has a saturation magnetization of 110.2 emu/g, a Curie temperature of 576 K, and an anisotropy field of 111 kOe. It is known that melt spinning is an effective means to obtain high coercivity of magnetically hard materials. In this work, the hard magnetic properties of melt–spun Sm2Fe15Al2C1.5 alloys were investigated. It was found that the value of coercivity depends strongly on the quenching rates and an optimum coercivity of 9.4 kOe was obtained at the quenching rate of 20 m/s. X-ray diffraction patterns indicate that the as-quenched ribbons have a phase of the Th2Zn17-type structure. The high coercivity of these as-quenched ribbons originates from the excellent intrinsic magnetic properties of Sm2Fe15Al2C1.5. It can be concluded that the substitution of Al is very effective in raising the coercivity of melt–spun Sm2Fe15Al2C1.5 ribbons.