Analysis of creep behaviour of TiAl-8Ta intermetallic alloy

Abstract

The creep behaviour of a high Ta containing γ-TiAl alloy was investigated in the temperature range of 700-850°C with applied stresses in order to have rupture times up to 3000 h. Decelerating primary and accelerating tertiary regimes dominated the experimental curves, whilst the secondary regime with constant minimum creep rates was absent. Reporting the experimental data in plot log vs. the tertiary data lie on lines with similar slopes at all temperature and load conditions, indicating that a damage mechanism, depending only on the accumulated creep strain causes the accelerating tertiary regime. Creep tests with step like changes in load and/or temperature changes were run and microstructure investigations were performed through X ray diffraction, scanning and transmission electron microscopy to have an insight on the nature of the damage mechanisms that control the accelerating tertiary regime. © 2010 IOP Publishing Ltd.