Crystallization and magnetic properties of rapidly thermal annealed amorphous Sm2Fe15Ga2C2 melt-spun ribbons

The amorphous Sm2Fe15Ga2C2 ribbons were rapidly thermal annealed at various temperatures for various times. From the X-ray diffraction patterns, two p hases, i.e. 2 : 17 phase and alpha-Fe, were always found when the ribbons w ere annealed at temperature above 700 degrees C. The demagnetization curves also verified this two-phase behavior. However, from the TEM studies, only 2: 17 phase was found. This led to the suggestion that the alpha-Fe precip itates were caused by the oxidation of Sm and only took place at the surfac e of the annealed ribbons. Moreover, from the TEM images, crystallization o f 2 : 17 phase was found to begin at about 600 degrees C. The ribbons annea led at 700 or 900 degrees C for 1 min showed well-defined grains in the abs ence of alpha-Fe. Their grain sizes were measured to be about 100 nm for 70 0 degrees C x 1 min and 250 nm for 900 degrees C x 1 min, respectively. It was thus suggested that the Sm2Fe15Ga2C2 2 : 17 type structure obtained fro m the melt-spinning technique remains stable up to at least 900 degrees C. (C) 1999 Published by Elsevier Science B.V. All rights reserved.