High temperature mechanical properties of a submicrocrystalline Ti-47Al-3Cr alloy produced by mechanical alloying and hot isostatic pressing

High temperature tensile properties of a TiAl-based alloy with a submicrocr ystalline structure were studied in the temperature range of 800 to 1200 de greesC and the strain rate range of 10(-4) to 3x10(-1) s(-1). The alloy was produced by hot isostatic pressing of an amorphous mechanically alloyed po wder and contained two phases, TiAl and Ti2AlN; the latter resulted from co ntamination of the powder with nitrogen during mechanical alloying. Two tem perature ranges with different behavior were distinguished. In the temperat ure range of 800 to 950 degreesC, the stress exponent, n=6, and the activat ion energy of deformation, Q=497 kJ mol(-1), were typical to a climb contro lled deformation mechanism. In the temperature range 1000 to 1200 degreesC, the stress exponent, n=3, and the activation energy, Q=347 kJ mol(-1), wer e determined together with high elongation indicating superplastic behavior . (C) 2000 Elsevier Science B.V. All rights reserved.