Effects of sintering temperature of whisker preform on the microstructures and tensile properties of Bi(OH)3-coated Al18B4O33 whisker-reinforced aluminum matrix composites

A alumina borate whisker with Bi(OH)3 coating was prepared by a chemical method. The coated whiskers were sintered at various temperatures. The coated whisker-reinforced pure aluminum matrix composite was fabricated by squeeze casting method. The microstructures of the coated whiskers and coated composites with the different sintering temperature of whisker preform were studied, and the tensile properties of the coated composites at room temperature were also investigated. It can be found that the microstructures of coatings on the whisker surfaces and at the interface in the coated composites are strongly dependent on the sintering temperature of whisker preform. The ultimate tensile strength and elongation to fracture of the coated composites increased with the increasing of sintering temperature of the whisker preform.

► Sintering temperature results in coating structure changing from Bi2O3 to Al4Bi2O9.
► When the whisker preform was sintered at 830 °C, whisker and Bi2O3 can react.
► Sintering temperature had a significant impact on microstructure of coated composites.
► Reaction between whisker and Bi2O3 improved tensile properties of coated composite.