Deformation Behavior and Strengthening Mechanisms of a Typical Bimodal L12 Precipitates Strengthened Nickel-Based Superalloy Over a Wide Range of Strain Rates and Temperatures

Abstract

Nickel-based superalloys with bimodal L1₂ precipitates have been widely used in extreme environments due to their excellent mechanical properties. However, limited studies have focused on the deformation behavior and mechanisms under combined high strain rates and high temperatures. In this study, uniaxial compression experiments were conducted on a typical bimodal L1₂ precipitates strengthened nickel superalloy over a wide range of temperatures (293–1273 K) and strain rates (1 × 10⁻³ s⁻¹–5 × 10³ s⁻¹) to reveal the coupling effect of temperature and strain rate on the mechanical behavior. The results show that the mechanical behavior is highly sensitive to temperature and strain rate, with the alloy exhibiting remarkable high temperature strength, particularly under dynamic loading. The third-type strain aging (3rd SA) effect is observed in this alloy, and its underlying mechanism is analyzed. Microstructural characterizations are conducted at various conditions, providing multiscale insight into the intricate relationship between microstructure and property. A transition in dominant deformation mechanisms is observed, shifting from anti-phase boundary dislocation pair shearing to stacking fault as temperature increases. Additionally, a comprehensive diagram is provided to elucidate the deformation mechanisms of the alloy under a wide range of strain rates and temperatures.