Decomposition and crystallization in undercooled liquid and amorphous Co 72Fe 4.5Cr 1.5Si 12.5B 9.5

Abstract

Experimental data are presented on surface and bulk crystallization in as-cast and annealed samples of a Co 72Fe 4.5Cr 1.5Si 12.5B 9.5 ribbon. The data suggest that (i) surface crystallization on melt spinning is preceded by phase separation of the undercooled melt into B- and Si-enriched phases, the short-range order in the latter phase, s cp, being similar to that of the close packed structures, (ii) the s cp phase decomposes on annealing of as-cast samples, the decomposition gives rise to the Fe-enriched phase s bcc with the bcc-like short-range order and (iii) the s bcc and s cp phase separated domains act as precursors of the bcc and hcp crystals of Co-based solutions, respectively.