具有不同梯度晶粒组织的粉末高温合金疲劳小裂纹扩展原位观察  

In-situ observation of short crack growth behavior for powder superalloys with different gradient grain microstructures

作　　者：朱磊 王易成[2] 张皓 陈阳 江荣 宋迎东 ZHU Lei;WANG Yicheng;ZHANG Hao;CHEN Yang;JIANG Rong;SONG Yingdong(AECC Hunan Aviation Powerplant Research Institute,Zhuzhou 412002,China;College of Energy and Power Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;AECC Bejing Institute of Aeronautical Materials,Beijing 100095,China)

机构地区：[1]中国航发湖南动力机械研究所,株洲412002 [2]南京航空航天大学能源与动力学院,南京210016 [3]中国航发北京航空材料研究院,北京100095

出　　处：《粉末冶金技术》2023年第5期420-426,共7页Powder Metallurgy Technology

摘　　要：采用扫描电子显微镜原位观察的方法对某第三代粉末高温合金不同微观组织的疲劳裂纹萌生和小裂纹扩展行为进行了研究,揭示了双性能粉末涡轮盘轮缘(粗晶组织)、轮心(细晶组织)及晶粒过渡区(梯度结构组织)的微观组织对疲劳小裂纹扩展的影响规律。结果表明:缺口处的一次强化相易成为裂纹萌生位置,其中梯度结构组织呈现出从晶界处开裂的多裂纹萌生特征。对于梯度结构试样,室温下的小裂纹扩展行为受微观结构影响显著,疲劳裂纹扩展速率波动较大。在应力强度因子范围较低时,粗晶试样的裂纹扩展速率高于细晶;随着应力强度因子范围逐渐增大,细晶试样的疲劳裂纹扩展速率增加更快,并高于粗晶试样;这与较长的滑移路径、增强的滑移可逆性和较少的晶界阻碍、减弱的不连续度之间的竞争机制相关。The fatigue crack initiation and short crack propagation behavior of a 3rd generation powder superalloy with the different microstructures were studied by in-situ scanning electron microscope(SEM)observation.The effects of microstructures at the wheel rim(coarse grain structure),wheel centre(fine grain structure),and grain transition zone(gradient grain tructure)of the dual performance powder turbine disk on the fatigue short crack propagation were investigated.The results show that,the crack prefers to nucleate from the first hardening phase at the notch.The gradient microstructure exhibits the multiple cracking at the grain boundaries.For the specimens with the gradient microstructure,the short crack growth behavior at room temperature is significantly affected by the microstructures,and the fatigue crack growth rate shows the large fluctuation.At the lower stress intensity factor range,the crack propagation rate of the coarse grains is higher than that of the fine grains.With the increase of stress intensity factor range,the crack propagation rate of the fine grains is increased faster and finaly higher than that of the coarse grains,which mainly attributes to the competition mechanism of the long slip path,the enhanced slip reversibility,the few grain boundary barriers,and the reduced discontinuity.

关 键 词：粉末高温合金 原位观察 疲劳小裂纹 晶粒尺寸 梯度结构 

分 类 号：TF123[冶金工程—粉末冶金] V231.95[冶金工程—冶金物理化学]