(1. 北京有色金屬研究總院, 北京 100088；
2. 清華大學(xué) 材料系， 北京 100084)
摘 要: 對晶須添加的方向角效應(yīng)進(jìn)行了研究，對裂紋尖端后方晶須橋連角度引起的應(yīng)力重新分配進(jìn)行了有限元分析，得到晶須添加角度不同時Si3N4陶瓷材料的裂紋尖端和晶須附近區(qū)域的應(yīng)力應(yīng)變場。分析表明，試件在Ⅰ型加載受力狀態(tài)下，當(dāng)添加晶須的軸向垂直于裂紋面時，晶須在裂紋尖端后方的橋接所引起的能量耗散作用最大，添加效果最優(yōu)，使材料達(dá)到較好的增韌效果。當(dāng)添加晶須與裂紋面法向形成角度θ時，隨角度θ的增加，裂紋尖端拉應(yīng)力增加。 當(dāng)添加角度較大時，晶須根部基體承受了較大的應(yīng)力， 易遭到破壞性崩裂。同時，晶須內(nèi)部主應(yīng)力與晶須軸向之間的角度也隨角度 θ 的增加而增加，造成晶須折斷，致使造成晶須撥出的體積分?jǐn)?shù)φap減小，降低了增韌效果。
關(guān)鍵字: SiC晶須； Si3N4； 橋連； 有序添加角度； 增韌機(jī)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
