Failure mechanism of molybdenum-rhenium alloy

The mechanism is studied of the plastic fracture of high-strength wires made of a molybdenum-rhenium alloy. In the course of plastic deformation, long before fracture initiation, a break-up of the starting material into separate areas takes place. At the later stages of deformation nucleation cracks appear in the resultant structure. The cracks form at the fragment joints, i.e. in those places where the shift vector or rotation vector undergo the maximum disturbance and where the material is under the heaviest stressed conditions and deformation-weakened to the maximum extent. The continued deformation leads to a gradual opening of the cracks along the fragment boundaries. The fact that the cracks initiate and propagate in the already developed fragment structure, after it has reached the critical and final stage of its development, is supported by the complete agreement between the topologies of the cracks and the fragments. It follows from the study of the sample lateral surface relief, the fracture surface relief and the topology of the microcracks that the fracture occurs predominantly along the subgrain boundaries appearing in the process of deformation prior to fracture