Microstructure and mechanical properties of γ base titanium aluminide produced from extruded elemental powders

Abstract

An elemental powder mixture of composition Ti–35 wt-%Al was cold extruded, reactive hot isostatic pressed at 1000°C, and subsequently annealed at 1250°C. A duplex microstructure was formed having elongated lamellar regions of Ti3Al/TiAl within a TiAl matrix. Specimens were tested in compression at temperatures between room temperature and 900°C. The material exhibits good deformability at 700°C and above. In this region, the typical stress–strain behaviour accompanying dynamic recrystallisation is observed. Matrix and lamellar regions both undergo deformation. Below 700°C, pseudoplasticity occurs, which is related to homogeneous formation of microcracks. The observed behaviour is compared with that of a cast material of similar composition.MST/1545