(1. 沈阳工业大学 材料科学与工程学院，沈阳 110870；2. 沈阳黎明航空发动机股份有限公司，沈阳 110043)
摘 要: 通过测定一种镍基单晶合金的蠕变曲线和观察微观组织及对合金断裂后位错组态进行分析，研究中温高应力条件下镍基单晶合金的组织演化及断裂特征。结果表明：在760 ℃、700 MPa条件下，合金蠕变断裂后的断口表面由类台阶状形貌组成，且台阶取向相同，台阶的两个棱边与á110ñ晶向平行，台阶的上平面平行于{001}晶面。合金凝固形成的共晶区是合金薄弱区域，裂纹在该区域萌生和扩展，并最终导致合金的蠕变断裂。800 ℃、750 MPa蠕变期间，合金中的g ¢相可形成与应力轴垂直的类N−型筏状结构，但筏状g ¢相的尺寸较短，在合金的g基体通道及g ¢/g两相界面处存在大量位错网，有部分á110ñ超位错切入筏状g ¢相内。(1/2) 位错由g ¢/g相界面切入 g ¢相后发生位错分解，可形成(1/3)á112ñ超肖克莱不全位错+层错的位错组态，当有单个位错穿过层错区时，致使位错与层错衬度相互重叠，使层错条纹明暗衬度发生变化。
关键字: 单晶镍基高温合金；断口表面；蠕变；组织演化；位错
（1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;
2. Shenyang Liming Aero-engine Corporation, Shenyang 110043, China）
Abstract:By measuring the creep curves, observing the microstructure and analyzing dislocation configuration of the nickel-base single crystal superalloy after being fractured at medium temperature and high stress, the rupture fracture surface characters and deformation mechanism of the nickel-base single crystal superalloy were studied. The results show that, the rupture fracture surface is made of lots of steps plane, which posses the same orientation and two edges with á110ñ orientation for each step, and the upper plane of step parallel to the {001} plane faces after creep up to fracture at 760 ℃ and 760 MPa. The formed eutectic area during lasting solidification is the weak area where the crack initiation and propagation happen during creep, eventually lead to alloy creep rupture. The formed N-shape like ordered g ¢ phase structure vertical to the stress axis during creep at 800 ℃ and 750 MPa, but the raft length of ordered g ¢ phase is shorter. There are lots of dislocation nets in matrix channel and ordered g ¢/g two-phase interface place, and a part of á110ñ super dislocations shear the ordered g ¢ phase raft. The dislocation is decomposition into partial dislocation (1/3)á112ñ + stacking fault configuration when the (1/2) dislocation shears the g ¢ phase through g ¢/g phase interface. When a single dislocation slips through the stacking fault area, the dislocation and stacking fault overlap, and the dislocations lining stripe light and shade changes.
Key words: single crystal nickel-base superalloy; fracture surface; creep; microstructure evolution; dislocation
