Microstructure evolution and damage mechanism of layered titanium matrix composites under tensile loading

Abstract

In order to better guide the design of layered metal matrix composites, the failure mechanism of a kind of Ti based layered composite was investigated. The results showed that this layered composites possessed better uniform deformation ability compared with the materials of each layer. Increasing the hard composite layer thickness led to the enhancement of tensile strength but descend of deformation ability. The micro-cracks in the Ti layer provided plasticity, while the unique network microstructure in the composite layer restrained the slip bands from the network central region. These slip bands propagated through network skeleton and caused TiB whiskers fracture and interface debonding between the metallic matrix and TiB whiskers. Numerical simulation indicated that interface cracks in the composite layer were prone to propagate first. Larger composite layer thickness led to crack convergence more likely to occur and thus resulted in the drop of ductility with increasing the hard composite layer thickness.