The tensile deformation mechanisms of [011]-oriented Ni-based single crystal superalloy: from experiments and molecular simulations

The tensile deformation of [011]-oriented Ni-based single crystal superalloys was studied across temperatures (20-850°C) and strain rates (0.0001-0.01/s) using experiments and molecular dynamics. With increasing temperature, the fracture morphology evolved from pure cleavage to cleavage with extensive tearing edges and sparse micropores. A strong strain rate sensitivity and a pronounced yield drop were observed at 850°C under low strain rate of 0.0001/s. Strain rate governs the dislocation mechanism by regulating the dynamic competition between dislocation multiplication, storage, and recovery. At high temperatures and low strain rates, the yield drop originates from the depinning of dislocations from γ/γ′ interfaces, which induces a sudden reduction in slip resistance. Under constant strain rate conditions, this reduction leads to a pronounced stress drop. This work clarifies the depinning-induced yield drop and the role of strain rate in storage-recovery competition, deepening the understanding of the deformation mechanisms of [011]-oriented nickel-based superalloys.