CHARACTERIZATION AND MICROANALYSIS OF INTERFACIAL REACTIONS IN METAL-MATRIX COMPOSITE SYSTEMS

摘要

Understanding the solid-state reactions involved in metal/ceramic systems is important when combining the two types of materials into a composite, In this investigation, the solid-state reaction between Al2O3 (alumina) and a beta-Ti alloy has been characterized by transmission electron microscopy (TEM), scanning electron microscopy, parallel-acquisition electron energy-loss spectroscopy and X-ray energy-dispersive spectroscopy. Two different systems were used to investigate this reaction. The first system utilizes a controlled reaction geometry and involved diffusion bonding single-crystal alpha-alumina and a beta-Ti alloy. Here, three interfacial regions were found to form: a region of intermetallics (Ti3Al and TiAl) located near the alumina interface, an alpha-Ti region, and a beta-Ti region (rich in Mo, the beta-phase stabilzer). Analysis of cross-section TEM samples of this reaction revealed the presence of both Ti3Al and TiAl at the alumina interface. Orientation relationships between the intermetallics and the alumina are discussed. In the second, system, interfacial reactions inside metal-matrix composites that contain alumina and a beta-Ti alloy were investigated. Here, different coatings used in the MMCs are investigated for their ability to prevent the reaction between the matrix and fibres. Reaction products inside the MMCs are compared with those found in the model reaction geometry. [References: 14]