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通过对一种镍基单晶合金进行中温不同应力条件下的蠕变性能测试及组织结构与断口形貌观察,研究了合金在蠕变期间的损伤及断裂机制。结果表明:合金在蠕变后期的变形机制是主、次滑移系的交替开动,主/次滑移系的多次交替开动,可在两滑移系交错区域的γ′/γ两相界面萌生裂纹;随蠕变进行,沿与应力轴垂直的γ′/γ两相界面发生裂纹的扩展,形成与<110>方向平行的正方形解理面,其中,裂纹在(001)面沿<110>方向扩展,与{111}二次解理面相截时,可终止裂纹扩展。这是使(001)解理面具有四方形特征的原因。由于蠕变期间在不同横断面发生多个微裂纹扩展,并在裂纹尖端沿较大剪切应力方向形成撕裂棱或发生二次解理,使多个裂纹连通,直至发生蠕变断裂。这是使合金蠕变断口呈现凹凸不平多层次解理特征的主要原因。
The creep property and microstructure and fracture morphology of a nickel-based single crystal alloy under different temperatures were investigated. The damage and fracture mechanism of the alloy during creep was investigated. The results show that the deformation mechanism of the alloy at the late creep stage is that the primary and secondary slip systems are alternately started and the primary / secondary slip systems are alternately activated multiple times, and the deformation mechanisms of the alloys at the γ ’/ γ two-phase interface Initially, cracks propagate along the γ ’/ γ interface perpendicular to the stress axis, forming a square cleavage plane parallel to the <110> direction, where the (001) plane along the > Direction of expansion, and {111} secondary cleavage plane phase, the termination of crack growth. This is why the (001) cleavage plane has a square shape. Due to multiple micro-crack propagation in different cross-sections during creep and the formation of tearing edges or secondary cleavage along the direction of larger shear stress at the crack tip, multiple cracks are communicated until creep rupture occurs. This is the main reason for the multi-level cleavage characteristics of the alloy creep fracture.