Tensile fracture of iron-iron aluminide foil composites

Abstract

Because intermetallics have limited ductility, it is not possible to form composite structures that require extensive plastic deformation during processing. However, the formation of metal-intermetallic composites by Self-propagating, High-temperature, Synthesis, (SHS) reactions has the advantage that materials may be preformed into the desired final shape prior to forming the intermetallic phase. Recently, the SHS process has been used to form metal-intermetallic composites in one step processing. Metal-metal aluminide composites were formed by sandwiching Al sheets between Fe, Ni, or Ti sheets. Then, by heating the layered composition, an SHS reaction occurred at the metal-aluminum interface. The resulting exothermic reaction melts the aluminum which then reacts with the surface of the other metal producing a liquid intermetallic phase. When the metal-intermetallic system cools the resulting structure is a tightly bonded layered composite. The fracture characteristics of any material and especially of composites are important to know before applications can be found for the material. The initiation and propagation of cracks in one of the composite phases, and the propagation of cracks through the interface and through the second phase controls the eventual failure of a material. In this study, iron-iron aluminide composites formed by SHS reactions were evaluated for tensile propertiesmore » and failure characteristics.« less