Microstructure and mechanical properties of Fe3Al-based alloys with strengthening boride precipitates

Five quaternary Fe-Al-B-M (M = Ti, Hf, Zr, V, W) alloys based on Fe3Al with strengthening boride precipitates were produced by vacuum induction melting. The alloys were investigated with respect to their microstructure and mechanical behaviour up to 1000 °C. The mechanical properties were determined by tensile tests, 4-point-bending tests, high-temperature compression tests up to 1000 °C as well as creep tests at 650 and 750 °C. Microstructural and phase analysis were carried out by light optical microscopy, scanning electron microscopy, X-ray diffraction analysis and differential thermal analysis. The alloys were tested in the as-cast state, after homogenisation at 1200 °C for 48 h and after annealing at 800 °C for 624 h. Compared to a corresponding binary alloy the examined alloys exhibit significantly improved mechanical high-temperature properties as well as stable microstructures without considerable loss of ductility.