Microstructural study of high coercivity Sm(Co,Cu)5 alloy

Magnetic measurements, X-ray and microstructural studies are carried out in as-cast and in annealed Sm(Co-0.5,Cu-0.5)(5) showing high coercive field. In the as-cast state three regions with different (Sm, Co, Cu)-content were found. The annealed samples showed a more homogenised composition but still with a two region microstructure. One of the regions has a higher (Sm, Cu)-content. X-ray diffraction patterns show only a CaCu5-type structure while microprobe analysis shows a higher Sm content than the Sm(Co, Cu)(5) composition for all regions in the as-cast and the annealed sample. Optical micrographs and Kerr microscopy show for the annealed sample grains with heavy faulting. The evolution of the microstructure upon annealing is discussed in relation with the Sm excess and Cu incorporation into the CaCu5-type structure. The relation between the observed microstructure and the magnetic behaviour is also discussed. (C) 1999 Published by Elsevier Science B.V. All rights reserved.