Microstructure and Mechanical Properties of Al2O3p/AZ91 Magnesium Matrix Laminated Material Adjusted by Freezing Temperature

The Al2O3 laminated preforms with different layers thickness were prepared by freezing casting in present work. Then, the Al2O3p/AZ91 magnesium matrix laminated materials were obtained by infiltrating the AZ91 alloy melt into the Al2O3 laminated preform based on pressure infiltration process. Subsequently, the influence of freezing temperature on the microstructure, mechanical properties and fracture behavior of magnesium-based laminates was investigated. The results indicated that with the decrease of freezing temperature, the thickness of Al2O3 layers decreases gradually, the number of layers increases obviously, and the interlayers spacing decreases. Accompanied with the decrease of interlayers spacing, the size of Mg17Al12 phase precipitated in the AZ91 alloy layers was refined, and the compression strength and strain were both improved obviously. The micro-cracks initiated in Al2O3 layers during loading process, while the AZ91 layers could effectively suppress the initiation and propagation of micro-cracks. Furthermore, the changing layers structure influenced by the decrease of freezing temperature had significant inhibiting effect on the initiation and propagation of micro-cracks, which endowed the Al2O3p/AZ91 magnesium matrix laminated materials with better strength and toughness. Notably, the best compression properties of Al2O3p/AZ91 magnesium matrix laminated materials could be obtained at the freezing temperature of - 50 degrees C, the compression strength and elastic modulus of which were the 160% and 250% of monolithic AZ91 alloy, respectively.