MICROSTRUCTURE AND MECHANICAL-BEHAVIOR OF IN-SITU DIRECTIONAL SOLIDIFIED NIAL CR(MO) EUTECTIC COMPOSITE/

NiAl-based composites reinforced with refractory metals in-situ by the directional solidification technique have been recognized as promisin g candidate materials for high temperature structural applications. An in-situ NiAl/Cr(Mo) eutectic composite has been successfully fabricat ed using an edge-defined film-fed growth technique. The purpose of add ing Mo into the NiAl/Cr eutectic system is to control the morphology o f the Cr from a fibrous to a lamellar structure. Microstructure and ch emical compositions were analysed using a scanning electron microscope with energy dispersive spectroscopy and a transmission electron micro scope. The mechanical behavior of the composite, including fracture re sistance and tensile properties at room and elevated temperatures, was studied. Damage evolution and fracture characteristics at room and el evated temperatures were also investigated. Copyright (C) 1996 Acta Me tallurgica Inc.