L1 2 (Al,Cr) 3Ti-based two-phase intermetallic compounds-I. Plastic deformation behavior

Abstract

A number of recent works on intermetallic compounds in the Ti-Al system have concentrated on gamma-based TiAl, but Al{sub 3}Ti is especially attractive because of its low density and good oxidation resistance. However, Al{sub 3}Ti, with a low-symmetry tetragonal D0{sub 22} structure, exhibits less than 1% compressive strain in the temperature range of 298 K to 893 K, for which the primary deformation mode is ordered twinning. Therefore, its brittleness limits its practical application as a structural material. More recently, much work has been conducted on the transformation of crystal structure through the addition of ternary alloying elements to improve the ductility of Al{sub 3}Ti. In this study, the plastic deformation behavior of two-phase intermetallic compounds consisting of mainly L1{sub 2} phase and the second phases in Al-Ti-Cr system was investigated. As in the case of {alpha}{sub 2}/{gamma} two-phase TiAl compounds, the possibility of ductilizing two-phase intermetallic compounds based on L1{sub 2}-type (Al,Cr){sub 3}Ti was examined. The influence of pore formation, ingot cast structure and second phase morphology on ductility of the alloy was also examined.