Deformation and Fracture Behaviour of Single Fibre Coated with Ductile or Brittle Layer

Abstract

In order to get a fundamental knowledge on metal matrix composites, experiments on deformation and fracture behaviour of single ductile fibre coated with ductile layer and that of single brittle fibre coated with brittle layer were carried out. For ductile fibre/ductile layer system, deformation parameters concerning the dynamic nature of plastic deformation and its relation to thermally activated dislocation mechanisms were measured. The deformation parameters obey the derived rule of mixtures in the whole range of plastic deformation, indicating that the inherent features of the fibre in the present composite system were conserved beyond the failure strain of the fibre tested alone. On the basis of this observation, a possible mechanism was suggested to explain why ductile fibre is able to be elongated beyond its failure strain when embedded in ductile layer. For brittle fibre /brittle layer system, deformation and fracture behaviour was studied on the emphasis of effects of interfacial bonding strength. A theoretical model of fracture mode and tensile strength was presented as a function of the thickness of brittle layer, which described well the experimental results.