Microstructures and mechanical properties of Fe–Al–Ta alloys with strengthening Laves phase

The addition of Ta to Fe–Al alloys results in the formation of a stable Ta(Fe,Al)2 Laves phase with hexagonal C14 structure in the Fe–Al phase at temperatures of 800, 1000 and 1150 °C. It was found that the solubility of Ta in Fe–Al is generally low and the solubility of Ta varies with Al content. Respective isothermal sections of the Fe–Al–Ta system have been established. Particular attention has been given to precipitation in the Fe3Al phase with a small addition of Ta. At intermediate temperatures, 600–750 °C, an additional Heusler-type phase with L21-structure precipitates, which transforms at longer times and high temperatures to the stable C14 Laves phase. The yield stress in compression and the creep behaviour of the Fe–Al–Ta alloys with various microstructures were studied. Due to the presence of the L21-Heusler phase, the yield stress and the creep resistance at temperatures below 700 °C was increased considerably.