Abstract
Creep experiments were conducted on Fe-25 at. pct Al-5 at. pct Zr alloy with carbon additions at the temperatures of 973 K and 1173 K (700 A degrees C and 900 A degrees C). The alloys were tested in two different states: (i) cast and (ii) annealed at 1273 K (1000 A degrees C) for 50 hours.
Stress exponents and activation energies were estimated. The values of the stress exponent n could be explained by the dislocation motion controlled by climb.
The increased values of n in the high-carbon alloy at the temperature of 1173 K (900 A degrees C) can be described by means of the threshold stress concept. The creep resistance at 973 K (700 A degrees C) decreased with the increasing content of carbon.
This result is discussed in terms of the ratio of zirconium to carbon in the alloy. An increase of the creep resistance with increasing ratio Zr:C is in agreement with the behavior observed previously in alloys with substantially lower concentrations of zirconium.