【摘要】 通过蠕变性能测试和组织观察,研究4.5%Re/3%Ru镍基单晶合金在高温的蠕变行为和损伤特征。结果表明:测定出该合金在(1100℃, 140 MPa)下的蠕变寿命为476 h。合金在高温稳态蠕变期间的变形机制是位错在γ基体中滑移和攀移越过筏形γ′相,在蠕变后期的变形机制是位错在基体中滑移和剪切筏状γ′相。其中,剪切进入γ′相的位错可由{111}面交滑移至{100}面,形成的K-W锁+APB组态,可改善合金的抗蠕变性能。随着大量〈110〉位错的交替滑移使筏状γ/γ′两相扭曲、折断及筏状γ′相的晶体旋转,使其成为亚晶结构,可降低合金的蠕变抗力。两滑移系的交替开动可使筏状γ/γ′两相界面出现微裂纹,并沿与应力轴垂直方向发生裂纹的扩展,直至蠕变断裂,是合金在高温蠕变后期的损伤与断裂机制。更多还原

【Abstract】 The creep behavior and damage feature of a 4.5%Re/3%Ru-containing single crystal nickel-based superalloy at high temperature were investigated of creep property measurement and microstructure observation. The results show that the creep life of alloy at(1100 ℃, 140 MPa) is measured as 476 h. During steady state creep at high temperature, the deformation mechanism of alloy is dislocation slipping in γ matrix and climbing over the rafted γ′ phase. In the later stage of creep, the deformation mechanism of alloy is dislocations slipping in γ matrix and shearing into the rafted γ′ phase. Wherein the dislocations shearing into γ′ phase can cross-slip from {111} to {100} planes to form the configuration of K-W locking + APB, which may improve the creep resistance of alloy. The alternated slipping of a large number of 〈110〉 dislocations causes both the twisting and breaking of the rafted γ/γ′ phases and the crystal rotation of γ′ phase to form the sub-grain structure, which may reduce the creep resistance of alloy. Furthermore, the alternated activation of the initiation/secondary slipping systems may promote the initiation of cracks occurring in the rafted γ/γ′ interface, and the cracks are propagated along the interface perpendicular to the stress axis until creep fracture, which is the damage and fracture mechanism of alloy in the later stage creep at high temperature.更多还原