The Compressive Deformation Behavior of Long Range Ordered Polycrystalline iron—aluminum Alloys

Abstract

Abstract The compressive deformation behavior of polycrystalline iron‐aluminum alloys has been investigated (i) at 298°K for specimens heat treated in various ways and containing from 22.0 to 31.7 at% Al, and (ii) from 77 to 655°K for well‐annealed specimens containing 26.6 at% Al. Alloys which possess significant DO 3 type long range order exhibit marked composition and temperature dependent variations in deformation behavior. Specifically, those containing ⪆ 27 at% Al exhibit two linear and one parabolic deformation stage at 298°K. The linear stages are shown to be a result of the production and motion of DO 3 type superlattice dislocations. The absence of these stages in well‐annealed specimens is attributed to the lack of thermal assistance for the DO 3 superlattice dislocation nucleation process. The flow stress levels which characterize the two linear stage behavior agree with calculations of the stress required for production of antiphase boundaries. Results obtained from quenched specimens are in agreement with the above conclusions, and the changes induced by quenching are in accord with calculations of the effect of thermal antiphase boundaries upon dislocation motion.