晶须增韧陶瓷刀具材料的R曲线与增韧机理的关系

The Correlation Between R-Curve Behavior and Toughening Mechanisms of Whisker Toughened Ceramic Material

采用维氏压痕／断裂压力法对Al2O3／SiCw陶瓷刀具材料的裂纹扩展阻力曲线进行了测试．结果表明，裂纹扩展量较小时，R曲线较陡；裂纹扩展量较大时，R曲线趋于平缓．通过裂纹扩展量参数λ的计算，定量地分析了Al2O3／SiCw陶瓷刀具材料的增韧机理，当裂纹扩展量小于参数λ时，晶须桥接是断裂韧性提高的主要原因；而裂纹扩展量大于λ时，晶须拔出是重要的增韧机制；裂纹的偏转对断裂韧性的提高也是有贡献的．

The crack-growth-resistance behavior or R-curve behavior of Al2O3/SiCw ceramic cuttingtool material was obtAlNed by employing the Vickers indentation/fracture stress technique. TheR- curve exhibits a steeply rising part while the crack extension is at its initial stage and thefracture toughness increases gently with tile crack propagating further. The quantitative analysisof toughening mechanisms indicates that whisker bridging is the mAlN cause of ascending fracturetoughness at the initial stage of crack extension less than λ, however, whisker pull-out operatessignificantly in toughening behavior with the increase of crack cxtension. Additionally, crackdeflection also contributes to the increase of fracture toughness.