Microstructure and properties of in situ nanometric Al2O3 reinforced α-Fe(Al)–Fe3Al-based composites

The alpha phase Fe(Al)–Fe3Al-based composites reinforced with 4–9 vol.% α-Al2O3 dispersions were fabricated by hot-pressing sintering. Nanometer-sized α-Al2O3 dispersed homogeneously in the submicron α-Fe(Al) and Fe3Al matrix, with a 20% lattice-mismatch presented between α-Al2O3 and α-Fe(Al). Higher fracture toughness (39 MPa m1/2) and bending strength (1260 MPa) were obtained for composites containing both intragranular and intergranular Al2O3 grains. The combination of fine grain strengthening with dispersion strengthening can account for the improvement of mechanical properties.