Effect of molybdenum substitution on the yield stress anomaly in Fe3Al-based alloys

We report on the phase stability and high-temperature strength of (Fe1−xMox)3Al with 0 ≤ x ≤ 0.20. As the D03–B2 transition temperature Tc increases by the Mo substitution, the yield stress peak substantially shifts to higher temperatures and can be found at about 900 and 970 K for x = 0.05 and 0.10, respectively. The strain rate sensitivity is near zero in the temperature range where the plateau with a rather low yield stress appears, but rises sharply around the peak temperature, reaching a maximum at the very vicinity of Tc. The close correlation between the peak temperature and the transition temperature strongly supports that the loss of D03 order is responsible for the occurrence of the yield stress anomaly.