Characteristic and mechanical properties of magnesium matrix composites reinforced with Mg2B2O5w and B4Cp

Squeeze casting technique was used to fabricate Mg2B2O5w/AZ91D singular composite and (Mg2B2O5w + B4Cp)/AZ91D hybrid composite to study the effect of Mg2B2O5w and B4Cp hybrid reinforcements on magnesium alloy. The microstructure, mechanical properties and fracture features of the composites were investigated. The results show that the additions of Mg2B2O5w and B4Cp can remarkably enhance the flexural properties of the composites. Especially, B4Cp has a larger contribution to the flexural strength and flexural modulus of the hybrid composite. The flexural strength of the hybrid composite is 29% higher than that of the singular composite. The reason can be ascribed to the higher dislocation density in the matrix of the hybrid composite due to larger differences in the elastic modulus and CETs between B4Cp and the matrix than those between Mg2B2O5w and the matrix. On the fractured surfaces of the composites, most of Mg2B2O5w and B4Cp fracture in the matrix, suggesting that the interfacial bonding strength between the reinforcements and the matrix is relatively strong.