【摘要】 通过对6%Re/5%Ru单晶镍基合金(质量分数)进行蠕变性能测试和组织观察,研究了合金的超高温蠕变行为和影响因素。结果表明:测定出合金在(1160℃,120 MPa)的蠕变寿命为206 h。中期稳态阶段,位错在基体中滑移和攀移越过γ′相是合金的变形特征,γ基体中溶解的难熔元素可增加位错在基体中运动的阻力。超高温蠕变期间,随温度提高γ′相发生溶解,可减小筏状γ′相的尺寸,提高位错攀移越过γ′相的速率,特别是当温度大于1170℃时,合金的施加温度敏感性使筏状γ′相的尺寸减小,应变速率提高,这是合金蠕变寿命大幅度降低的主要原因。蠕变后期,基体位错可在位错网破损处切入γ′相,其中,切入γ′相的位错可由{111}面交滑移至{100}面形成K-W锁,抑制位错的滑移和交滑移,可改善合金的蠕变抗力。而在颈缩区域较大的有效应力可开动位错的双取向滑移,致使筏状γ′相扭折,并在扭折区域发生裂纹的萌生和扩展,直至断裂,这是合金在超高温蠕变期间的变形和损伤机制。更多还原

【Abstract】 Through the creep properties test and microstructure observation of a 6%Re/5%Ru single crystal nickel-based superalloy, the ultra-high temperature creep behavior and influencing factors of the alloy were studied. The results show that the creep life of the alloy at(1160 ℃, 120 MPa) is 206 h. The deformation features of alloy in the middle creep period is large number of dislocations sliding in γ matrix and climbing over γ′ phase, the refractory elements dissolving in γ matrix may increase the resistance of dislocation movement. During creep at ultra-high temperature, the γ′ phase dissolves as the temperature increases, which can reduce the size of the rafted γ′ phase and increase the rate of dislocations climbing over the rafted γ′ phase. Especially, when the temperature is higher than 1170 ℃, the applied temperature sensitivity of the alloy diminishes the size of the rafted γ′ phase and increases the strain rate, which is the main reason for drastically reducing creep life of the alloy. In the later creep period, the dislocations can shear into γ′ phase from the damaging region of dislocation networks. The K-W locks can be formed by the cross-slip of dislocations from the {111} plane to the {100} plane, which can inhibit the slip and cross-slip of dislocations. The larger effective stress in the necking area can activate the double orientations sliding of dislocations, causing the rafted γ′ phase to twist, and crack initiation and propagation in the contorted regions until fracture, which is the mechanism of the deforming and damaging features of alloy during creep at ultra-high temperature.更多还原