High strength and high fracture toughness ceramic−iron aluminide (Fe3Al) composites

Fe3Al-based composites reinforced with micron-sized titanium carbide, tetragonal zirconia and nano-scaled alumina particles were hot-pressed, and the room temperature mechanical properties were investigated. Results show that nano-Al2O3 is not an efficient ceramic for the enhancement of mechanical properties of Fe3Al, primarily due to its inhomogeneous distribution and severe agglomeration within the matrix as well as the weak interfacial bonding. By contrast, Fe3Al/5 wt.% ZrO2 composite had a strength as high as 1361 MPa and a fracture toughness of 19.0 MPa m. The enhancing effect is attributed to the low thermal expansion mismatch between ZrO2 and Fe3Al matrix, and to the stress-induced transformation of ZrO2 particles. The flexural strength and fracture toughness for Fe3Al/10 wt.% TiC composite was 1086 and 20.0 MPa m, respectively. The mechanical properties of Fe3Al/TiC composites decreased with TiC content above 10 wt.% due to the suppression of plastic deformation, residual porosity and interfacial debonding.