The glass-forming ability (GFA) of RE-AI-TM (RE = Sm, Y; TM = Fe, Co, Cu) u
pon melt-spinning and die-casting into a copper mold has been studied. Melt
-spun ribbons for both Sm- and Y-based alloys show a fully amorphous struct
ure. However, die-casting revealed that Sm-based alloys exhibit a higher GF
A than Y-based alloys. The as-cast Sm70Fe20Al10, Sm60Fe20Al10Co10 and Sm60F
e20Al10Co5Cu5 cylinders (3 mmx50 mm) contain a mixture of amorphous and cry
stalline phases after copper-mold casting. A new bulk metallic glass was ob
tained for the Sm60Fe10Al10Co15Cu5 alloy, which shows ferromagnetic behavio
r. In contrast, as-cast Y-based alloys are completely crystalline. Based on
the data of the activation energy for crystallization of the amorphous pha
se, E-x, and the crystallization temperature, T-x, together with magnetic m
easurements, it is concluded that the as-cast Sm60Fe10Al10Co15Cu5 cylinder
displays a tendency for clustering. The improved glass-forming ability of S
m-based alloys is interpreted in terms of classical nucleation theory. (C)
2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights r
eserved.