Fe3Al Composites Strengthened and Toughened by Multi-walled Carbon Nanotubes

Novel Fe3Al composites strengthened and toughened by 1vol%, 3vol%, 5vol% and 7vol% multi-walled carbon nanotubes (MWNTs) were fabricated by spark plasma sintering (SPS). X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were carried out to determine the phase composition, and to analyze the microstructure and crack propagation of the composites. Fracture toughness and compressive yield strength were determined at room temperature. Then, the strengthening and toughening mechanism of MWNTs in the composites were discussed. Experimental results show MWNTs keep perfect structure intact in the composite. The fracture toughness and compressive yield strength of composite with 3vol% MWNTs reach the maximum values of 40 MPa·m1/2 and 3175 MPa, respectively. The bridging effect on cracks and pullout of MWNTs are possible strengthening and toughening mechanisms.