Effect of the interfacial bonding status on the tensile fracture characteristics of a boron–fiber-reinforced aluminum composite

The effect of the interfacial bonding status on the tensile fracture characteristics of a boron–fiber-reinforced aluminum (B/Al) composite has been studied by scanning electron microscopy (SEM). Four kinds of interfaces were studied, i.e., interfaces with chemical reactants and three other types of interfaces without chemical reactants but with weak, strong and appropriate B/Al interfacial bonding strengths, respectively. For the sample with chemical reactants at the B/Al interfaces, which were induced by the interfacial reactions during the materials processing, the fracture surface was observed as the flat type, with cracks initiated at the interfaces and propagated across the fibers. However, for the sample with weak B/Al interfacial bonding, the fracture surface was observed as the fiber pullout, nonflat type, and the B/Al interfaces were separated after failure due to the weak interfacial bonding. On the other hand, for the sample with strong interfacial bonding, the fracture surface belonged to the flat type with broken boron fibers and well-bonded B/Al interfaces, which were classified as the type III fracture morphology of the boron fibers, whereas in the sample with appropriate interfacial bonding strength the fracture surface exhibited fracture features of both the samples with weak and strong interfacial bonding. The tensile strength of this sample with appropriate interfacial bonding was found to be the highest among all the types of interfaces studied.