Abstract
The magnetic properties and crystal structures of nanocrystalline Sm-Fe-Co-Nb-B compounds were studied using rapid quenching technique and powder x-ray diffraction analysis. As a result, it was found that the TCu7-type structure was able to be obtained even if the B content of the ribbons was around 8at%, and high magnetic properties was obtained. In over-annealing conditions, the TbCu7-type structure transforms to Sm2(Fe, Co)14B1 and α-(Fe, Co) phases. Optimizing the compositions and preparing conditions, the following results have been obtained; compositions: Sm6.2Fe82.8-xCoxNb2.7B8.3(x=12-16); roll surface velocity: 16-18m/s; annealing conditions: 640°C×(1.5-2.5)h; magnetic properties: HCJ, =0.55-0.60 MA/m, Br=0.85-0.95T, (BH)max=100-120kJ/m3; temperature coefficients: -α=0.05-0.06%/°C, -β=0.33-0.35%/°C. Curie temperature: Tc>500°C, Grain size of the ribbon was about 20nm and halo component in x-ray pattern was around 30%. Outside the suitable composition or annealing conditions, Sm3(Fe, Co)62B14, Sm2(Fe, Co)23B3, Sm2(Fe, Co)14B1 or α-(Fe, Co) phases appeared.
