Effect of the withdrawal rate on the microstructure and creep behavior of the directionally solidified nickel-based superalloy

The effect of the withdrawal rate on the microstructure and creep behavior of a directionally solidified nickel-based superalloy DZ125L is investigated in this study. A directionally solidified nickel-based superalloy is directionally solidified using the high rate directional solidification (HRS) process at various withdrawal rates. The results show that the closely packed dendrite arms and well distributed γ′ phase can significantly enhance the creep rupture life of the alloys, while the carbides and γ/γ′ eutectics affect the strength failure and fracture of materials. A series creep tests are performed on the nickel-based directionally solidified superalloy after different withdrawal rates. With an increasing withdrawal rate, the creep life of the alloy first increases and then decreases. The K–R creep damage model is established, which can reflect the quantitative relation between the withdrawal rate and creep life. The model simulation results are in good agreement with the tests.