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摘要: 用透射电子显微镜和扫描电子显微镜研究了一种镍基合金(Nimonic 75型)蠕变-疲劳交互作用的机制。在温度873K,应力幅392MPa下进行的实验表明,蠕变、疲劳和“蠕变叠加疲劳”数据近似满足线性积累损伤规律。扫描电子显微镜断口观察表明,所有试样均发生晶间型断裂。但用透射电子显微镜进行的位错观察指出,在蠕变、疲劳和“蠕变叠加疲劳”试样中,位错组态有明显的差别。这些不同的位错组态,对晶间断裂过程产生了各自不同的影响,因而蠕变损伤与疲劳损伤相互独立,在宏观上表现出线性交互作用的规律。本工作表明,透射电子显微
Abstract: The mechanism of creep-fatigue interaction in a nickel base alloy (Nimonic 75 type) has been studied by transmission and scanning electron microscopy. Experiments at 873 K and a stress amplitude 392 MPa showed that, the data of creep, fatigue and "creep combined with fatigue" obeyed approximately the linear cumulative law. Micrographs of fracture surfaces by SEM indicated that, the rupture was all intergranular. However, observations by TEM showed that, the dislocation configurations within fractured specimens were quite different among creep, fatigue and "creep combined with fatigue". We believe that different dislocation configurations have different influence on the process of intergranular rupture, and the damages due to creep and fatigue are independent with each other. Consequently, linear interaction between creep and fatigue occurs macroscopically. The present paper shows that TEM has great potentialities for revealing the mechanism of creep-fatigue interaction.