Low-temperature superplasticity in ultrafine-grained Ti5Si3–TiAl composites

A ceramic–intermetallic composite of Ti5Si3 with 40 vol.% TiAl was synthesized by mechanical alloying and hot isostatic pressing. The microstructure consisted of equiaxed grains of γ-TiAl and ζ-Ti5Si3 with a size of about 400 nm. This composite exhibited a tensile elongation of 150% at 950 °C, using a strain rate of 4 × 10−5 s−1. This temperature for superplastic deformation is just about 0.5 Tm, the lowest normalized superplastic temperature reported for any ceramic-based material.