Creep behavior of Al-rich Fe-Al intermetallics

The compression creep behavior of two dual-phase intermetallic alloys (FeAl2-Fe2Al5 and FeAl3-Fe2Al5) was investigated over the temperature range 600-1000 °C. A normal primary creep stage, stress exponent between 4 and 5, and normal creep transient after a stress increase for the FeAl2-Fe2Al5 and FeAl3-Fe2Al5(T> 700 °C) materials suggest that the creep behavior of both is controlled by a dislocation climb process. The activation energy for creep for both materials is about 345 kJ mol-1. For FeAl3-Fe2Al5 tested at 700 °C, a stress exponent of 3.3 and an inverse creep transient after a stress increase suggest that viscous dislocation glide is the dominant deformation mechanism in this region. The activation energy for creep in this region is 280 kJ mol-1. The creep strength for FeAl2-Fe2Al5 is significantly lower than that for FeAl3-Fe2Al5. A comparison between FeAl3-Fe2Al5 and various Ni and Ti aluminides reveals that FeAl3-Fe2Al5 has superior specific strength except compared with TiAl.