TEM studies of melt-spun alloys with liquid miscibility gap.

The microstructures of the Fe-Cu-based alloys melt-spun from various temperatures are presented. Two compositions, with different Fe and Cu content, revealing liquid miscibility gap, were studied. Nonuniform, large-elongated areas were observed for lower melt-spinning temperatures, indicating liquid/liquid phase separation in the crucible before cooling. An increase of the melt ejection temperature, followed by rapid cooling, brought about precipitation process within homogeneous melt. Studies of the system with higher Fe content proved amorphous nature of the matrix and crystalline structure of the primary formed Cu-rich precipitates. Moreover, generations of the secondary spherical particles, precipitated within the previously formed Cu-rich melt, were observed. The microstructure of the melt-spun alloy with a higher Cu content, on the other hand, consisted of the Fe-rich amorphous spherical particles formed during cooling of the Cu-rich liquid. The precipitation of the secondary Cu-rich particles in the primary formed Fe-rich was also observed.