Microstructure and Mechanical Properties of TiAl/Ti<SUB>2</SUB>AlN Composites Prepared by Combustion Synthesis

Abstract

TiAl/Ti2AlN composites were prepared by a reactive arc-melting technique using elemental powders of Ti, Al, and AlN . Ti2AlN particles synthesized by the combustion reaction synthesis were dispersed in the lamella grains, with rod-like shapes with sizes of 1–3 \\micron width and 5–15 \\micron length. The grain size of the matrix was decreased and the deviation of the grain size was converged by the distribution of the Ti2AlN . The lamella grains in the matrix were decomposed both into TiAl and very fine Ti2AlN particles by the homogenizing treatment. The bending strength of these composites was larger than that of TiAl single-phase material and it was improved by increasing the Ti2AlN content. Their ductility kept the same level of that of TiAl. Fracture toughness values were enhanced by the dispersion of Ti2AlN, since crack propagation can be deviated by such dispersoids in the composite materials.