| An attempt has been made to investigate the effects of SiC volume fraction on the fracture toughness. Especially to estabilish the relationship between fracture toughness and microstructure in this composires, micromechanical fracture behavior in front of crack tip was examined quantitatively. It was possible to decide the average tensile strain in the process zone, ε￣ by experimental method. The microstructural distance r^* which can correlate a fracture toughness value with the microstructure was obtained by substituting εfor ε^p of HRR solution. According to the fracture criterion which was observed in this study, r^* was related to the spacing of critical particle diameter, d_(crit). From the above analytic method, following equation was obtained. J_(ic)=ασ_yε￣_fd_(crit). where α : constant(α=2I_N/ε^p(θ,N)) ε￣_f : average tensile fracture strain in a process zone d_(crit) : inter-particles spacing of a critical particle diameter |
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