Revealing the fatigue crack initiation mechanism of a TiB_2-reinforced steel matrix composite

摘要

The initiation of fatigue cracks in a TiB2-reinforced high-modulus, low-density steel was revealed by in-situ scanning electron microscopy for the first time. The results show that the superior interfacial strength between the TiB2 particles and the matrix prevents the initiation of micro-cracks at the interfaces. Fatigue micro-cracks are mainly induced by the brittle fracture of small eutectic TiB2 particles, while the coalescence of these micro-cracks plays the major role in the fatigue failure. This failure mechanism is essentially different from the static tensile failure mode in which the large primary TiB2 particles are the main source of fracture failure.