Evaluation of Mechanical Properties Variations for Kr Ion‐Irradiated 6H‐SiC by Nanoindentation Methods

Nanoindentation experiments were performed to investigate the irradiation effects on the mechanical properties of 6H‐SiC irradiated by 4 MeV Kr ions at high fluences from room temperature ( RT ) to 550°C. The irradiation temperature is the primary factor that affects modifications of the comprehensive mechanical properties, while the effect of the fluence is less significant. Elastic modulus and hardness decrease drastically for RT ‐irradiated samples, but they almost recover for elevated temperature samples, with hardness slightly higher than its original value. The hardness increases first and then decreases with increasing temperature, and the elastic modulus decreases linearly as the swelling increases. Meyer's index is related to the indentation size effect of hardness and the magnitude of the lattice damage. The ratio of irreversible work is associated with the degree of elastic recovery and the ratio of hardness to elastic modulus of SiC. Compared with the unirradiated value, fracture toughness changes slightly for RT irradiation, while increasing significantly for elevated temperature irradiation and has the same variation tendency of hardness. Results indicate that mechanical properties change with the variations of interatomic bond strength, dislocation mobility, and the behavior of crack propagation, which is strongly affected by the defects induced by heavy‐ion irradiation.