Two-fold flow stress anomaly in L21-ordered Fe–Al–Ti-based alloys

During investigations of the mechanical properties of L21-ordered Fe–Al–Ti-based alloys, a two-fold flow stress anomaly has been detected. This stress anomaly is marked by two distinct flow stress peaks at around 500 and 750 °C. While the peak at about 750 °C has been reported before, the occurrence of a second peak is reported for the first time. It has been investigated by means of compression tests at various compression rates and after different heat treatments of the alloys, measurements of the hardness after water quenching from relevant temperatures and by differential thermal analysis. The results give no clear insight into the mechanism of this two-fold anomaly. However, it can be seen that aging at around 500 °C and increasing the compression rate from 10−4 to 10−2 s−1 have an effect on the phenomenon.