ABSTRACT Understanding the fatigue behavior of silicon carbide (SiC) is critical for its deployment in high‐temperature environments. This work utilizes large‐scale molecular dynamics simulations to investigate fatigue‐crack propagation in both single‐crystal and polycrystalline 3C‐SiC, considering varied strain ratios ( R = 0.4–0.6), strain rates (10 9 –10 11 s −1 ), and temperatures (300–1500 K). A lower strain ratio ( R = 0.4) enhances fatigue life by approximately 50%, owing to crack tip amorphization that mitigates local stress concentration. Under high strain rates (10 11 s −1 ), dynamic amorphization is promoted, which reduces crack‐propagation rates by up to 40.5% and increases the fracture toughness ( K IC ) by 16.3% in single‐crystal samples. Temperature exhibits the most pronounced effect: At 1500 K, polycrystalline SiC suffers a 71.6% reduction in K IC , with failure transitioning to a cooperative multigrain boundary network mechanism. Notably, cyclic loading at 1500 K leads to significantly lower amorphous content (7.4%) compared with monotonic loading (27.8%), hinting at a potential recovery‐like process during unloading phases. These atomic‐scale insights highlight microstructural and grain boundary engineering as promising strategies for improving the fatigue resistance of SiC.
Zeng et al. (Tue,) studied this question.