Synthesis of TiAl(Cr)/Ti₂AlC Composites by Reactive Arc-Melting

Abstract

TiAl(Cr)/Ti₂AlC composites have been prepared by a reactive arc-melting technique using elemental powders of Ti, Al, Cr and C . Resulting composites have been reinforced using 3.5, 10 and 18 vol% Ti₂AlC in a matrix of TiAl with and without addition of Cr. The axial ratio of γ-phase has been lowered through the complete solid solution of chromium. The grain size of the matrix has been found to decrease whereas its distribution converges along the content of Ti₂AlC . The lamella grains in the matrix have been changed both into TiAl and very fine Ti₂AlC particles by a homogenizing treatment. Compared to TiAl single-phase alloy, studied composite materials have revealed superior mechanical properties, such as bending strength, compressive strength and fracture toughness. This improvement is caused by the formation of Cr solid-solution for hardening, dispersion of the Ti₂AlC particles and the fine grain of the TiAl matrix.