Microstructure and properties of the in situ formed amorphous-crystalline composites in the Fe–Cu-based immiscible alloys

Abstract

The paper presents microstructures and mechanical properties of the melt-spun Fe 30Cu 32Si 13B 9Al 8Ni 6Y 2 and Fe 44Cu 18Si 13B 9Al 8Ni 6Y 2 alloys. It was found that liquid phase separation of the initially homogeneous melt occurred due to a positive heat of mixing between two major elements. The microstructures of the melt-spun ribbons were composed of the Fe-rich amorphous and the Cu-rich crystalline phases. A significant effect of the melt ejection temperature and the chemical composition (Fe and Cu content) on microstructures of rapidly solidified alloys was revealed. The microstructures of ribbons melt-spun from the miscibility gap region were non-uniform. On the other hand the microstructures of ribbons melt-spun from homogeneous melt temperature region were composed of the spherical precipitates distributed within the matrix. Superior hardness values of the examined ribbons melt-spun from the same temperature were found for the alloy with higher iron content. An increase of the melt-ejection temperature in the homogeneous melt region resulted in hardness decrease in case of the Fe 30Cu 32Si 13B 9Al 8Ni 6Y 2 alloy and its increase for the Fe 44Cu 18Si 13B 9Al 8Ni 6Y 2 ribbons.