Published online by Cambridge University Press: 22 February 2011
The effects of heat treatment at 1150°C on the creep-rupture properties of a Fe3Al-based alloy were studied. Tests were conducted in air using various test temperatures and stresses. By plotting the data to a power-law equation, the activation energy for creep was determined to be approximately 150 kcal/mole and the creep exponent to be about 8. Optical metallography and scanning electron microscopy of ruptured specimens indicated that failure occurred in a ductile manner by microvoid coalescence at grain boundaries and triple points. Analytical electron microscopy was used to study characteristics of the microstructure and to identify Zr-rich precipitates that formed during heat treatment or creep testing. These precipitates were found to provide strengthening by pinning dislocations and grain boundaries.