Formation of Nanocrystalline Globules and Metallic Glass in Fe70-xCuxZr10B20 (x=0–70) Alloys

The microstructure in rapidly-solidified Fe70-xCuxZr10B20 (x=0, 10, 20, 30, 35, 60 and 70) alloy ribbons prepared by single-roller melt-spinning method was examined. In spite of the positive heat of mixing in Fe–Cu atom pair, metallic glass was formed in Fe–Cu–Zr–B ribbons. F.c.c.–Cu nano crystalline globules dispersed in Fe–Zr–B based metallic glass was formed in Fe60Cu10Zr10B20 and Fe50Cu20Zr10B20 alloys. Size of the globules in nano-emulsion structure increased with increasing Cu concentration. In Fe35Cu35Zr10B20 and Fe10Cu60Zr10B20 alloys, an entangled marble-like duplex structure composed of Fe-rich and Cu-rich crystalline phases was formed. Zr and B additions in Fe–Cu based alloys cause the formation of metallic glass and unique solidification structures in rapidly solidified melt-spun ribbons.