Studies on the structure and magnetic properties of Sm-2(Fe,Al)(17)C-Y alloys with Zr additions

The microstructure and magnetic properties of induction-melted and melt-spu n Sm-2(Fe,Al,Zr)(17)C-gamma samples with Zr additions have been systematica lly studied using X-ray diffraction, TEM, differential thermal analysis, an d magnetic measurements. The results show that the induction-melted and mel t-spun Sm-2(Fe,Al,Zr)(17)C-Y samples have a multi-phase structure with the 2:17-type carbide, alpha-Fe and ZrC phases. Both the Curie temperature and the lattice parameters of the 2:17-type structure are found to be almost co nstant with Zr addition but the saturation magnetization decreases with inc reasing Zr content. The addition of Zr is effective at eliminating alpha-Fe dendrites and preventing the precipitation of large size alpha-Fe phase th rough rapid quenching and annealing. The optimum coercivity of 11.6 kOe alo ng with a remanence of 55 emu g(-1) is obtained for a Sm2Fe15.3Zr0.2Al1.5C1 .5 ribbon spun at 40 m s(-1) and annealed at 750 degrees C for 30 min, It i s presumed that the high remanence and coercivity are due to the small crys tal size and significant exchange coupling at interphase boundaries. (C) 19 98 Elsevier Science S.A. All rights reserved.