Abstract: Using the experimental and theoretical methods, the tensile strengths and fracture mechanisms of Al2O3 short fiber reinforced Al-Mg alloy matrix composite at elevated temperatures were researched. The interfacial microstructural characteristics and the fracture surfaces of the composite at different temperatures were observed by transmission electron microscope (TEM) and by scanning electron microscope (SEM), respectively. Then, from the results of microscopic observation, the fracture mechanisms of the composite at different temperatures are discussed. Finally, the tensile strengths of the composite at elevated temperatures were predicted by statistical integration average (SIA) method with the consideratio of various fracture mechanisms. It was shown that the strengths and fracture mechanisms of the composite at elevated temperature (300°C) were significantly different from those at room temperature due to the variations of interfacial bonding states. The tensile strengths predicted by the SIA method at elevated temperatures agreed well with the experimental results.

Key words: Fracture, Al2O3, Al-Mg alloy, Composite