一种无铼二代镍基单晶高温合金蠕变机制研究

Creep Deformation Mechanism in the Rhenium Free Second Generation Nickel-base Single Crystal Superalloy

通过对一种镍基单晶合金中温高应力条件下的蠕变曲线的测定和微观组织及断裂后合金中位错组态的衍衬分析,研究中温高应力条件下单晶合金的组织演化及变形特征。结果表明:在中温高应力条件下,该合金的蠕变激活能Q为(462±20)kJ/mol,表观应力指数na=4.34。表明在试验温度和应力范围内,合金具有较好的蠕变抗力。位错组态衍衬分析表明,蠕变期间切入相内的<110>超位错既可在{100}立方体滑移系中运动,也可在{111}八面体滑移系中运动;位错在运动中相遇发生位错反应,形成的超位错可交滑移至{100}立方体滑移面。位于2个不同{100}六面体滑移面的位错在运动中相遇,可发生位错反应,生成的位错可在{111}八面体滑移系中运动。

By measuring the creep curves at medium temperature and high stress of a nickel-base single crystal superalloy and analyzing the microstructure and dislocation configuration diffraction after creep fracture, the microstructure evolution and deformation mechanismof the single crystal alloy were researched. The results show that the alloy creep activation energy Q is （462 ± 20） kJ/mol under the medium temperature and high stress conditions, and the apparent stress exponent na is 4.34, indicating that the alloy possesses better creep resistance in the measuring temperature and stress range. Dislocation diffraction contrast analysis indicates that the super dislocations 110 that cut into γ phase both slip in the {100} cube slip systems and in the {111} octahedral slip systems during creep. The dislocations of movement meet and a dislocation reaction can occur to form a super dislocation which can cross slip to the cube {100} slip plane. A reaction can occur for the motion dislocation which meet in two different six-sided {100} slip planes, and the resulting dislocation can move in the {111} octahedral slip systems.