Creep Fracture Behavior and Mechanism of a New Nickel-Based Single-Crystal Superalloy

Abstract:

A new type of nickel-based single-crystal superalloy was subjected to creep performance test, microstructure observation, and composition analysis under the condition of 1100 °C/140 MPa. The variation characteristics of the creep rate during the creep fracture process and the microstructure evolution before and after creep were investigated, thereby revealing the creep fracture mechanism of the new nickel-based single-crystal superalloy. The results indicate that the creep life of the alloy is 104.5 h, and the strain can reach 33.58%. The creep rate decreases first, then increases, and finally tends to be stable until fracture. At the initial stage of creep, the creep rate decreases first, then rises and finally decreases again with time. Furthermore, the creep fracture microstructure is composed of dimples and tearing edges without obvious slip planes. Oxides and recrystallized structures exist inside the fracture surface, and the voids inside the fracture are elongated and perpendicular to the stress axis, showing a fracture mechanism of microcrack accumulation.