【摘要】 利用改进压轮法预制出与以往不同的（１０）面［１１］方向的平直裂纹．采用三点弯曲法测定裂纹临界应力强度因子 Ｋ＿ｃ，用扫描电镜分析裂纹面断口的形貌，研究了硅单晶中的脆韧性转变（ＢＤＴ）行为 结果表明，随着加载速率从 ４μｍ／ｓ增加到 １６μｍ／ｓ，脆韧性转变温度向高温方向移动，转变区间由３５Ｋ减至狭小的８Ｋ，在这一区间内临界应力强度因子突然上升．在脆韧性转变过程中当裂纹扩展越过塑性饱和区后出现（１）和（１）面的交滑移，说明脆韧性转变与滑移系的启动有密切的关系更多还原

【Abstract】 The critical stre5s intensity factor K., fracture toughness was measured by means of three-point-bending method and SEM observation was made in order to Study the brittle-to-ductile transition (BDT) behaviour in a silicon single crystal. Pre-crack located in (1l0) pIane and along I11q direction was modified by indentation-wheeler technique. The resuIts show that the brittle-to- ductile transition temperature increases with the increasing of Ioad rate from 4pm/s to 16pm/s, but the temperature range of BDT decreases from 35K to 8K and K. exhibits an abrupt increasing in the BDT temperature range. The fracture propagates from saturation plastic zone to the zone with (11l) and (11l) plane cross-slip and the preliminary evidence indicates that the BDT behaviour is strongly dependent on the activation of slip systems.更多还原