【摘要】 采用声发射技术和高分辨X射线成像技术对SiC_f/Ti6242复合材料在热机械疲劳过程中的损伤进行了原位监测。实验中采用同相位梯形波加载来模拟钛基复合材料整体叶环服役时的实际载荷工况,应力变化范围130～1300 MPa,温度变化范围100～500℃,500℃时保持最大载荷2min。结果表明,声发射信号主要出现在加载阶段和保载阶段,声发射系统检测到纤维断裂、基体裂纹信号,而在卸载阶段声发射信号非常稀少。利用高分辨X射线成像技术对声发射确认已损伤的样品进行检查,发现试样内部存在连接多个纤维的基体裂纹;在样品裂纹区域,部分断裂纤维的钨芯出现缩颈。声发射技术和高分辨X射线成像技术均表明SiC_f/Ti6242复合材料热机械疲劳损伤机制由纤维断裂和基体裂纹共同控制。更多还原

【Abstract】 The damage of the SiC_f/Ti6242 composite in the thermomechanical fatigue test was monitored by the acoustic emission(AE) technique and the high-resolution X-ray tomography. The thermomechanical fatigue test was conducted with a trapezoidal waveform to simulate the actual loading of the bladed ring. The applied stress range was 130～1300 MPa and the temperature range was 100～500 °C. The maximum stress was held for 2 min at 500 °C. The AE events emerged mainly in the loading stage and the dwell stage for the cycle where the AE signals of fiber fracture and matrix cracking were found. The matrix cracks of the unbroken specimen were detected by the high-resolution X-ray tomography. The necking of the tungsten filament in the broken fiber in the cracking region was also found. These results show that the damage mechanism of the specimen is dominated by a mixture of fiber fracture and matrix cracking.更多还原