Microstructure And Properties Of Magnesium Borate Reinforced Aluminum Matrix Composites With Coated CuO

Firstly, CuO was coated on the surface of magnesium borate whiskers (MBO_w) using chemical method. Then, the aluminum composites reinforced by magnesium borate whiskers (MBO_w/2024Al) were fabricated by squeeze casting method, and the matrix was 2024Al. the volume fraction of the whiskers was about 25%.The microstructure of MBO_w/2024Al was observed with optical microscope (OM) and scanning electron microscope (SEM). The phase structure and microstructure of MBO_w was studied with SEM, TEM and X-ray diffraction (XRD). The interfacial reaction of MBO_w /2024Al was studied with XRD and TEM. The tensile properties were measured and analyzed. Thermal expansion behaviors of the composites were observed, and morn behaviors were measured. The influence of aging states on these properties was researched. The relationship between the tensile properties with the interfacial reaction was discussed in detail.The result had shown that interfacial reaction took place in squeeze casting process and its product includedγ-Al2O3. After solution treatment(490℃)for 2h,γ-Al₂O₃ and MgAl₂O₄ were found on the interface. The lattice relationship between reaction products and matrix was confirmed:γ-Al₂O₃, (220)γ// (220) Al and [ 111 ]_γ//[ 111 ]_Al ; MgAl₂O₄, (200)MgAl₂O₄// (220)Al and [100]MgAl₂O₄// [100]Al。Interfacial reaction was slight in the as-cast composites, and the interface was clean relatively. As the solution treatment time expanded, interfacial reaction became more obvious and more products were observed. In the process, products steps formed, grew up and disappeared in sequence. Interfacial reaction degree influenced the composites'properties obviously, including the Young's modulus, tensile strength, elongation percentage, yield strength, thermal expansion coefficient and worn rate. Relative to every property, there was perfect interfacial reaction degree respectively.Aging states also impacted notably the tensile strength, elongation percentage, yield strength, thermal expansion coefficient and worn rate.