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 gamma-TiAl and zeta-Ti5Si3 with a size of about 400 nm. This composite exhibited a tensile elongation of 150% at 950 degrees C, using a strain rate of 4 x 10(-5) s(-1). This temperature for superplastic deformation is just about 0.5 T-m, the lowest normalized superplastic temperature reported for any ceramic-based material. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.