Affiliation: | aGroupe de Métallurgie Structurale, ENSCP-CNRS, UMR 7045, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05, France bONERA/LEM, 29 Avenue de la Division Leclerc, F-92322 Chatillon Cedex, France cLaboratoire de Cristallochimie du Solide, Université Paris 6, 4 Place Jussieu, 75252 Paris Cedex 05, France dCECM/CNRS, 15 rue Georges Urbain, 94400 Vitry sur Seine, France |
Abstract: | Zr65Cu17.5Al7.5Ni10 (at.%) and Zr65Cu15Al10Ni10 (at.%) glass forming alloy microstructures have been investigated by means of optical and electron microscopies. They are composed of a fine eutectic matrix with eutectic dendrites (EDs) that have peculiar morphologies. Al and Cu concentrations, in these alloys, favour primary dendrites and determine the ED morphologies and compositions. Their locations within the microstructures suggest a two-step solidification process of the two undercooled melts. The identified crystalline phases indicate the occurrence of solid state phase transformations in agreement with the structural defects observed in the grains. The crystalline phases can be classified into Zr-rich, Cu-rich, Ni-rich and Al-rich compounds resulting from competing diffusion between Cu, Ni, and Al in the melts. |