Microstructure and metastalble phase formation in a rapidly solidified Ni-Si eutectic alloy using a melt-spinning technique

In the Ni-Si system, the eutectic structure composed of Ni-Ni3Si presents inherent thermal stability, allowing composite materials to be obtained with well-aligned and finely dispersed microstructures. The work reported here consisted of an investigation into the microstructure and morphology of such a eutectic alloy from the standpoint of its growth conditions. A Ni-Si eutectic alloy was processed by applying the directional solidification method at low growth rates and the rapid solidification technique using a melt-spinning process. The results indicate that samples processed under conditions close to equilibrium show a regular and aligned microstructure, while rapid solidification leads to an anomalous microstructure and the formation of a metastable phase. (C) 2004 Elsevier B.V. All rights reserved.38141671727