复合陶瓷含片状夹杂共晶体的理论断裂强度

Theoretical Fracture Strength of Composite Eutectic with Lamellae

应用四相模型法研究含片状夹杂复合共晶体的细观应力场．在基体、界面相和片状夹杂为各向同性的条件下，得到细观应力分布规律，并表现出明显的尺度效应．应用位错塞积理论研究片状夹杂内的位错运动，通过两相界面处位错塞积产生的应力集中确定其在基体内产生的最大张应力，导致基体首先被破坏失效，当基体内最大张应力等于分子理论的断裂强度时，得到共晶体断裂强度的理论表达式．结果表明：含片状夹杂共晶复合陶瓷强度随夹杂厚度增加而减小．

Based on four-phase-model, micro-stress field of eutectic composite with lamellae was obtained. On the conditions that matrix, interphase and lamellae were isotropic, the distribution of micro-stress field was determined and it was size-dependent obviously. Dislocation motion in la- mellae was investigated with the help of the dislocation pile-up theory. Tensile stress in matrix which lead to matrix break was determined by analysing the stress concentration at interphase. The theoretical fracture strength was obtained when the maximum tensile stress equal to molecu- lar breaking strength. Result indicates that fracture strength of eutectic composite deminishes as thickness of lamellae increases.