α'/β'-sialon陶瓷材料的循环疲劳裂纹扩展特性研究

CYCLIC FATIGUE CRACK GROWTH FROM VICKERS INDENTATION IN α ′/ β ′SIALON CERAMICS

研究了一种ｓｉａｌｏｎ陶瓷材料在循环疲劳载荷下Ｖｉｃｋｅｒｓ压痕短裂纹扩展特性。研究表明，最大应力强度因子与裂纹扩展速率之间呈Ｖ型扩展行为，并对外加应力水平非常敏感。由于残余应力的影响，起始很高的扩展速率随着裂纹的扩张而减少，而后裂纹扩展速率随应力强度因子的增加而增加直至快速断裂发生。如考虑残余应力强度因子的影响，裂纹扩展速率与有效应力强度因子之间关系符合Ｐａｒｉｓ公式，其幂指数ｎ为２７。

The cyclic fatigue crack growth behavior in gas pressure sintered α ′/ β ′sialon ceramics from microindentation flaws was investigated. A V shaped behavior was observed in the relation between the maximum applied stress intensity factor and the crack growth rate which is sensitive to the level of applied stress. The crack growth rate which is high at the initial stage of crack growth, reaches then a minimum and afterwards increases with the applied stress intensity factor until unstable fracture occurs. Crack growth data for all the level of applied stresses can be normalized by characterizing in terms of the residual stress intensity and the Paris power law exponent n =27.