温度对晶须增韧陶瓷刀具材料力学性能的影响 Ⅱ.高温断裂韧性的研究

Effect of Temperature on the Mechanical Properties of Whisker-Reinforced Ceramic Cutting Tool Material Ⅱ Study on High-Temperature Fracture Toughnes

采用表面受控裂纹法,在室温至1000℃范围内对SiC晶须增韧Al_2O_3陶瓷刀具材料JX-1的高温断裂韧性进行了测试和研究。结果表明,在低于800℃时,断裂韧性随温度变化很小,而在800℃以上断裂韧性随温度的升高而呈上升趋势。试件断口的SEM及TEM分析表明,高温下SiC晶须内部除低温存在的层错和孪晶结构外,还有大量位错的产生,并且晶须与基体的界面发生了塑性流动,。对加载速率对高温断裂韧性测试结果的影响也进行了研究。

CFS (Controlled Surface Flaw) was employed to test and examine high-temperature fracture toughness of Jx-1 SiC whisker -reinforced Al2O3 ceramic cutting tool material at temperature up to 1000℃ ,The results indicating that fracture toughness was not sensitive to temperature from room temperature to 800℃and it would increase as temperature rose at temperature above 800℃. SEM and TEM analysis of the fracture surfaces demonstrated that at high temperatures, there were a large amount of dislocations,besides stacking faults and twins found at low temperatures in SiC whisker and there was considerable plastic flow on -boundary between the whisker and the matrix. The effect of loading rate on high-temperature fracture toughness was also discussed.