The microstructure development in Fe32Cu20Ni28P10Si5B5 immiscible alloy and possibilities of formation of amorphous/crystalline composite

The microstructures of Fe32Cu20Ni28P10Si5B5 alloy representing the effects of slow cooling after arc melting and rapid cooling after melt spinning are shown. The slow cooling rate resulted in the fractal-like structures formed by the Fe-rich regions and Cu-rich regions typical for the alloying systems with a miscibility gap. The structures observed after rapid cooling were dependent on ejection temperatures of the alloy just before the melt spinning process. The lower ejection temperatures created crystalline structures separated into Fe-rich and Cu-rich regions as a result of rapid cooling within the miscibility gap. The higher ejection temperatures contributed to formation of amorphous/crystalline composite. The crystalline spherical precipitates were found to be predominantly Cu-base solid solution.