Abstrakt
Compressive creep of alloy based on Fe-30at.%Al with addition of 5.2 at.% zirconium was studied at temperatures from 650 to 900 degrees C. The alloy was tested in two different states: (i) cast and (ii) annealed at 1000 degrees C for 50 h.
The microstructure of cast alloy consisted of matrix (alpha/B2/D03) and fine lamellar eutectic composed of lambda(1) and (alpha/B2/D03). The eutectic decomposed during annealing at 1000 degrees C into lambda(1) and tau(1) phases.
Stress exponents and activation energies were estimated. The values of the stress exponent n can be explained by dislocation motion controlled by climb.
The values of the activation energy in both cast and annealed alloy are greater than the activation enthalpy of diffusion. Creep exposure at 900 degrees C for about 50 h is probably sufficient for attainment the three-phase structure because the same microstructure was observed after creep at 900 degrees C, in both as-cast and annealed states.
In contrast, creep expositions at 650 and 700 degrees C did not influence the appearance of microstructure.