(1. 北京有色金属研究总院, 北京 100088；
2. 清华大学 材料系， 北京 100084)
摘 要: 对晶须添加的方向角效应进行了研究，对裂纹尖端后方晶须桥连角度引起的应力重新分配进行了有限元分析，得到晶须添加角度不同时Si3N4陶瓷材料的裂纹尖端和晶须附近区域的应力应变场。分析表明，试件在Ⅰ型加载受力状态下，当添加晶须的轴向垂直于裂纹面时，晶须在裂纹尖端后方的桥接所引起的能量耗散作用最大，添加效果最优，使材料达到较好的增韧效果。当添加晶须与裂纹面法向形成角度θ时，随角度θ的增加，裂纹尖端拉应力增加。 当添加角度较大时，晶须根部基体承受了较大的应力， 易遭到破坏性崩裂。同时，晶须内部主应力与晶须轴向之间的角度也随角度 θ 的增加而增加，造成晶须折断，致使造成晶须拨出的体积分数φap减小，降低了增韧效果。
关键字: SiC晶须； Si3N4； 桥连； 有序添加角度； 增韧机制
（1. General Research Institute for Nonferrous Metals, Beijing 100088, P.R.China;
2. Department of Materials, Tsinghua University, Beijing 100084, P.R.China）
Abstract:The effect of additive orientation of SiCwhiskerwas studied, the stressredistribution caused by whiskerbridging orientation was analyzed by finiteelement method, and the stressstrain fields in zone of crack end with whisker were obtained at different additive orientations in Si3N4 ceramic material. When thespecimen was loaded by Ⅰ type, analysis results showed that the tensile stressin crack end and the main stress in whisker depended directly on the angle θ (angle between whisker axis and normal line of crack face). If θ=0, it means that whisker axis is perpendicular to crack face, the energy dissipation caused bywhiskerbridge join in zone of crack end achieves its maximum and the reintoughening effect of material achieves the best of all; along with growth of angle θ, the maximum principal stress in the matrix of whisker roots increases, when it achieves its limit, the whisker will be broken and orientation effect will be weakened.
Key words: SiC whisker; Si3N4; bridge join; additive orientation; reintoughening mechanism
