Effects of Cr2O3 coating of whiskers on the tensile properties and thermal stability of aluminum borate whiskers reinforced 2024Al composite

Cr2O3 coating of aluminum borate whiskers was prepared by sol–gel and Cr2O3-coated aluminum borate whiskers reinforced 2024Al composites were fabricated by squeeze casting. The coating process of Cr2O3 on aluminum borate whiskers and the effects of the coating content on the tensile properties of the composites were investigated. The interfacial microstructure of the composite after thermal exposure at high temperature for a long time was also investigated. The results show that Cr2O3 is uniformly coated on the surface of aluminum borate whiskers. The ultimate tensile strength and elongation to fracture of Cr2O3-coated aluminum borate whiskers reinforced 2024Al composite initially increase and later decline with increasing the coating content at room temperature. After thermal exposure at 490 °C for 50 h, there is no obvious change of interface microstructure, indicating the interfacial reaction of aluminum borate whiskers and magnesium in the matrix can be hindered effectively.

► Continuous Cr2O3 coating of aluminum borate whiskers (ABOw). ► Wettability of ABOw by molten 2024Al. ► Reactions between ABOw and magnesium in the matrix of 2024Al. ► Thermal stability of the composite at high temperature for a long time.