通过蠕变性能测试及组织形貌观察,研究含3%和5%(质量分数)Mo无Re单晶镍基合金的高温蠕变和损伤行为.结果表明:与3%Mo单晶合金相比,5%Mo无Re单晶合金具有较好的蠕变抗力和较长的蠕变寿命,测定出5%Mo单晶合金在1040℃、137 MPa的蠕变寿命为556 h.在施加的温度和应力范围内,测定出合金在稳态蠕变期间的表观蠕变激活能Q=484.7 kJ/mol.合金在稳态蠕变期间的变形机制是位错在基体中滑移和攀移越过筏状 γ′相;合金在蠕变较后阶段的变形机制是位错剪切进入筏状 γ′相.随蠕变进行,位错的交替滑移致使合金中筏状 γ′相发生扭曲,并在筏状 γ′/γ 两相界面发生裂纹的萌生和扩展,直至断裂,是合金在高温蠕变后期的损伤与断裂机制.
By means of creep property measurement and microstructure observation, the creep and damage behaviors of containing 3% and 5% (mass fraction) Mo single crystal Ni-based superalloy at high temperature were investigated. The results show that, compared to 3% Mo single crystal superalloy, the 5% Mo superalloy displays a better creep resistance and longer creep life, the creep life of alloy at 1040 ℃ and 137 MPa is measured to be 556 h. The deformation mechanisms of the alloy during steady state creep are dislocation slipping in γ matrix and climbing over the rafted γ′phase. In the later stage of creep, the deformation mechanism of alloy is dislocation shearing into the rafted γ′ phase. As the creep going on, the alternate activation of dislocations slipping resulted in the twisted of rafted γ′ phase promotes the initiation and propagation of crack occurring in the interface of γ/γ′ phase, until fracture, which is thought to be the damage and fracture mechanism of alloy during creep at high temperature.