Effects of coating contents on the interfacial reaction and tensile properties of Al2O3 coated-Al18B4O33w/Al-Mg matrix composites

Al2O3 was prepared on the surface of the Al18B4O33 whiskers by a hydrothermal synthesis method. Subsequently, Al2O3-coated Al18B4O33 whiskers reinforced Al-Mg matrix composites were fabricated by squeeze casting. The effects of Al2O3 coating contents on the interfacial reaction (between the whiskers and matrix) 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. MgO and MgAl2O4 were observed simultaneously at the interface of the composite in which the whiskers were not coated. However, only MgO was observed at the interface of the composites in which the whiskers were coated. The Al2O3 coating contents have an evident influence on the ultimate tensile strength (UTS) and elongation to fracture (δ) of the composites. The UTS and δ of the composites increase firstly and then decrease with the Al2O3 coating content increased. It is worth mentioning that the UTS of the composite with a suitable Al2O3 coating content can attain a highest value (490 MPa) in the as-cast Al18B4O33w/Al composites reported.