High temperature strengthening of the FeAl intermetallic phase-based alloy

The cause of the positive temperature dependence of the yield stress B2 FeAl alloys is still controversial. In the literature several models have been proposed but none of them fully accepted. In the present work results of studies of the yield stress, long range order parameter, magnetic susceptibility and structure versus temperature for the multi-component alloy on base of the B2 FeAl phase are presented.Results of TEM and HREM observations excluded precipitation hardening and the presence of antiphase domains as the reasons for the thermal hardening of the studied material. Detailed studies of the dislocation structure after small deformation of the alloy did not reveal the reaction of massive decomposition of the 〈1 1 1〉 superdislocation for the 〈1 0 0〉 and 〈0 1 1〉 in the temperature range of the anomaly occurrence.The plastic deformation process up to 1073 K proceeded by movement of the 〈1 1 1〉 type dislocations. For the first time a clear dependence of the yield stress temperature changes on the long range order parameter for the alloy on base of the B2 FeAl phase was obtained.