Influence of hot extrusion on the microstructure and mechanical properties of Al2O3/7075 aluminum matrix composites

Abstract The influence of hot extrusion on the microstructure and mechanical properties of Al 2 O 3 /7075 aluminum matrix composites was investigated via optical microscopy, scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, transmission electron microscopy and tensile testing. The results indicate that the yield strength, tensile strength, and elongation of the as-extruded composites respectively reached 244.4 MPa, 360.3 MPa, 11.0 %, which increased by 20.24, 33.28 and 507.73 %, compared to those of the as-cast composites. The hot extrusion process grants the composites fine compactness and significantly improves the distribution of Al 2 O 3 particles in the composite. The eutectic phase at the grain boundaries was crushed into small fragments under shear force after hot deformation. Moreover, high dislocation density near the Al 2 O 3 particles and grain boundaries was observed in the extruded composite. The failure mode of the as-cast material was quasi-cleavage fracture, while the failure mode of the as-extruded material was primarily ductile fracture.