54陶瓷的增韧 41陶瓷基复合材料 (a) Residual stress state around the dispersoid has 以G代替4来代表总的断裂功 a higher thermal expansion than the matrix(left) o=/)2 resulting in crack deflection(right) g(a)/=(EG)2 8 定义强度因子:K=o(ma)12 断裂韧性:K=(EG2 增韧机理 增韧机理(b) Crack bowing between dispersoid 增韧机理(c) Incorporation of metallic particles particles makes it possible for a crack to run around Bowed crack front °60。3° Primary crack front Direction of propagation 增韧机理(d) Whisker reinforcement involving debonding, deflection, and bridging 增韧机理(e)尹 Platelets bridging a crack Debonds Crack tip Matrix crack Whisker8 5.4 陶瓷的增韧 以Gc代替4γ来代表总的断裂功 1 2       = / a EGc f π σ σ(πa)1/2=(EGc)1/2 定义强度因子：K=σ(πa)1/2 断裂韧性：Kc =(EGc)1/2 增韧机理 (a) Residual stress state around the dispersoid has a higher thermal expansion than the matrix (left), resulting in crack deflection (right) Crack propagation σrr σθθ ap > α 5.4.1 陶瓷基复合材料 增韧机理(b) Crack bowing between dispersoid particles Primary crack front Direction of propagation Bowed crack front 增韧机理(c) Incorporation of metallic particles makes it possible for a crack to run around Crack tip Debonds (around whisker) Whisker SiC Matrix crack 增韧机理(d) Whisker reinforcement involving debonding, deflection, and bridging σa α β l t y 增韧机理(e): Platelets bridging a crack