Fracture behavior of monofilament-reinforced multicrystalline copper composites Original Research Article

Studies on monotonic tensile fracture and fatigue fracture have been performed on tungsten monofilament-reinforced multicrystalline copper composites and the failure modes are reported. Monotonic tensile fracture is not very sensitive to the initial fiber breaks and grain boundaries in tungsten monofilament-reinforced multicrystalline copper composites. Multiple breaks of the fiber and multiple necking of the matrix near the fiber segment breaks, commonly observed in tensile tests of composites, are reported here. However, the fatigue fracture is very sensitive to a fiber break, and to microstructural features such as grain boundaries and dislocation structures. Once the fiber breaks into two segments, the composite will quickly fail. The fatigue fracture mechanism of the composites depends on applied plastic strain amplitudes. Most cracks initiate at grain boundaries in the matrix at low and intermediate plastic strain amplitudes and the fiber greatly improves the fatigue behavior. At a high plastic strain amplitude, fatigue cracks initiate at the fiber, and the fiber seems ineffective for improving the fatigue life.