Glass forming ability and stability: ternary Cu bearing Ti, Zr, Hf alloys

Abstract

Four Cu bearing alloys of nominal composition Zr₂₅Ti₂₅Cu₅₀, Zr₃₄Ti₁₆Cu₅₀, Zr₂₅Hf₂₅Cu₅₀ and Ti₂₅Hf₂₅Cu₅₀ have been rapidly solidified in order to produce ribbons. All the alloys become amorphous after melt-spinning. In the Zr₃₄Ti₁₆Cu₅₀ alloy localized precipitation of cF₂₄ Cu₅Zr phase can be observed in the amorphous matrix. The alloys show a tendency of phase separation at the initial stages of crystallization. The difference in crystallization behavior of these alloys with Ni bearing ternary alloys can be explained by atomic size, binary heat of mixing and Mendeleev number. It has been observed that both Laves and Anti-Laves phase forming compositions are suitable for glass formation. The structures of the phases, precipitated during rapid solidification and crystallization can be viewed in terms of Bernal deltahedra and Frank-Kasper polyhedra.