The microstructure and tensile properties of Al2O3-coated Al18B4O33 whisker reinforced AA2024 aluminum composite

Abstract

The coating given to Al18B4O33 whiskers is expected to improve the interface bonding between the whisker/matrix and then to prevent the interfacial reaction. Al2O3 was firstly coated on the surface of the Al18B4O33 whiskers by a hydrothermal synthesis method. Al2O3-coated Al18B4O33 whiskers reinforced AA2024 matrix composites were fabricated by squeeze casting. The effects of Al2O3 coating on the interfacial reaction between the whiskers and matrix, the precipitated phase near the interface and the tensile properties of the composites were investigated. The results presented that the surface treatment of the whiskers can reduce the interfacial reaction effectively and affect the precipitated state of the matrix near the interface. In addition, it can be found that the Al2O3 coating on the surface of the whiskers can obviously enhance the tensile properties and improve the effect of aging strengthening of the composite. The hydrothermal temperature to prepare the coated whiskers had an obvious effect on the coating morphologies on the surface of the whiskers and the microstructure of the corresponding composite. As the hydrothermal temperature increased, the tensile properties of the composites obviously increased. When the coated whiskers were prepared at 200 °C, the highest ultimate tensile strength and elongation to fracture can be obtained in the corresponding composite, while simultaneously the effect of aging strengthen of the composite was also greatly advanced.