Effect of interfaces on the impact fracture characteristics of diffusion-bonded magnesium alloy ML-19

Magnesium and its alloys are used in various industries, particularly in the aerospace one. In this regard, the issue of increasing the structural strength of magnesium structures remains relevant. Impact strength is one of the structural strength criterions, that determines the reliability of a material in service. The application of the layering principle is a promising direction for improving this mechanical characteristic. In this study, the impact behavior of a layered material based on a magnesium alloy produced by diffusion bonding was investigated for the first time. Specimens of the layered and monolithic materials were tested at room temperature under impact bending tests with recording of dynamic loading diagrams. In addition to an impact strength, an impact fracture characteristic such as the total energy of fracture, crack initiation energy and crack propagation energy were quantitatively evaluated. The layered material was characterized by the highest impact strength when the crack propagated sequentially from one layer to another. The impact strength of the layered material when the crack propagated simultaneously through all the layers was comparable to that of the monolithic material. Regardless of the interface orientations relative to the direction of crack propagation in the layered material, the main contribution to the fracture energy was made by the energy of crack initiation, as in the monolithic material. However, for the monolithic material and the layered material when the crack propagated simultaneously through all layers, the crack initiation energy exceeded the crack propagation energy by 1.2 and 1.4 times, respectively. In contrast, for the layered material when the crack propagated sequentially from one layer to another, the crack initiation energy was 3.4 times higher than the crack propagation energy. Fracture of layered specimens was accompanied by the formation of delamination. Intergranular ductile fracture was observed in all impact specimens.