疲劳载荷下P／M Rene95合金中夹杂物的微观行为研究

Micromechanical Behavior of an Al_2O_3Seeded P/M Rene 95 Alloy under Cyclic Tensile Load

摘要:

采用人工植入Al2O3夹杂的试样，通过SEM下的原位试验，动态跟踪及分析了拉－拉疲劳载荷下P／M Rene95合金中表面或近表面夹杂物的微观行为。结果表明：在所研究的夹杂物的尺度范围内，载荷波形对夹杂物的微观力学行为有很大影响。在三角波加载条件下，虽然夹杂物／基体界面更易萌生裂纹，但表面或近表面夹杂物对试样的断裂影响较小；在正弦波载荷条件下，疲劳裂纹的萌生、扩展及试样的断裂均与表面或近表面夹杂物的基本特性有关。而且，降低正弦波加载时的应力幅值可大大提高夹杂物／基体界面疲劳裂纹的萌生寿命。

Abstract:

Specially designed SEM in situ fatigue tests have been conducted to trace the whole process of crack initiation and propagation to fracture in an Al2O3 seeded P/M Rene 95 superalloy.The results show that the loading wave shape has a strong effect on the micromechanical behavior.Under triangle wave loading crack initiation and propagation life decrease on the inclusion/matrix interface,but specimen failure is not due to the surface or sub surface inclusions.On the other hand,sine wave loading is accompanied by a significant increase the crack initiation life and surface or sub surface inclusions are always the primary cause of fatigue fracture.Furthermore,under the same loading waveform the crack initiation life increases as the amplitude of applied stress decreases.