The influence of B and Zr additions on microstructure, mechanical properties and oxidation behavior of cast ternary Fe-Al-Cr alloys

In this research, the influence of boron (B) and zirconium (Zr) additions on microstructure, mechanical properties and oxidation behavior of as-cast Fe-Al-Cr alloys was evaluated. The alloying process was carried out by vacuum induction melting. Microstructure evaluation, phase identification, compressive and tensile tests, the study of oxidation behavior and also fractography of the alloys were done. On the microstructure observations, the microstructure of the alloys are dendritic and precipitate phases typically present in interdendritic regions. Adding B and Zr create precipitate phases such as borides and Laves phases in the alloys. Zr has a much stronger effect than B on the improvement of high-temperature mechanical properties of this type of intermetallic compounds. Fractography of alloys shows that brittle fracture is dominant in the alloys, but allied additions cause to strengthen of grain boundaries by changing the fracture mode from intergranular to transgranular fracture mode. The oxidation resistance at temperatures up to 900 degrees C indicates a detrimental influence of Zr addition.