Abstract: Aluminum matrix composites with alumina particles of 40%(volume fraction) were fabricated using 5.0μm and 0.15μm Al2O3 particles respectively. The microstructure of the two kinds of composites before and after tension was investigated with transmission electron microscope (TEM). It was found that there was a high dislocation density in the as-cast composite reinforced by 5μm sharp-angle-shaped Al2O3 particle s, due to the thermal mismatch stress. In contrast, little dislocation was observed in the as-cast composite reinforced by 0.15μm spherical Al2O3 particles, which could be attributed to the following factors, such as the dispersion of the equiaxed fine particles, uniform distribution of the stress near the interfaces, etc. The microstructural observation near the fracture indicated that dislocations increased in the matrix of the former composite, while obvious dislocation loops were found in the latter. The room temperature tensile test confirmed that such microstructure in the sub-micro Al2O3p/Al composites was beneficial to an increase in their strength and ductility.
Effect of particle size and morphology on microstructure and properties of Al2O_ (3p) /Al composites
Abstract:
Aluminum matrix composites with alumina particles of 40% (volume fraction) were fabricated using 5.0?μm and 0.15?μm Al 2O 3 particles respectively. The microstructure of the two kinds of composites before and after tension was investigated with transmission electron microscope (TEM) . It was found that there was a high dislocation density in the as-cast composite reinforced by 5?μm sharp-angle-shaped Al 2O 3 particles, due to the thermal mismatch stress. In contrast, little dislocation was observed in the as-cast composite reinforced by 0.15?μm spherical Al 2O 3 particles, which could be attributed to the following factors, such as the dispersion of the equiaxed fine particles, uniform distribution of the stress near the interfaces, etc. The microstructural observation near the fracture indicated that dislocations increased in the matrix of the former composite, while obvious dislocation loops were found in the latter. The room temperature tensile test confirmed that such microstructure in the sub-micro Al 2O 3p/Al composites was beneficial to an increase in their strength and ductility.
Fig.1 TEM microstructures of Al2O3p/Al composites (φp=40%) (a) —5 μm-Al2O3p/Al; (b) , (c) —Bright field image and dark field image of 0.15 μm-Al2O3p/Al; (d) —Diffraction pattern of (b) and (c)
图2 Al2O3p/Al复合材料 (φp=40%) 拉伸变形后的显微组织 (TEM)
Fig.2 TEM microstructures of Al2O3p/Al composites (φp=40%) after tensile deformation (a) —5 μm-Al2O3p/Al; (b) —Bright field image of 0.15 μm-Al2O3p/Al; (c) —Dark field image of 0.15 μm-Al2O3p/Al