Carbide formation in Zr-containing Fe3Al-based alloys

The formation of carbides in Fe3Al-based alloys containing chromium, zirconium and carbon has been studied. Cr-Fe-carbides are generally observed in Zr-free material after heat treatment above 300 °C. Nevertheless, small additions of Zr entirely prevent their formation and fine-scale Zr-rich carbides are formed instead. These particles are found after hot rolling and subsequent cooling. They are stable up to 1000 °C. At higher temperatures, they partially dissolve and partially transform into coarse particles. These coarse particles do not dissolve even after annealing at 1350 °C for 2 h. Fine-scale Zr-carbides are difficult to form after high-temperature annealing and quenching. At temperatures ranging from 800 °C up to 1000 °C, carbides are formed in a very limited manner first at grain boundaries and, after longer annealing times, rarely also in the grain interiors.