Crystal Orientation Effect on the Irradiation Mechanical Properties and Deformation Mechanism of a-Fe: Molecular Dynamic Simulations

The crystal orientation effect on the mechanical properties and micro-deformation behavior of single crystal iron (SC Fe) were revealed by molecular dynamics (MD) simulations. The results show that the surviving defects in the SC Fe models are [110] < [100] < [111], and only the vacancy and interstitial atomic clusters are formed in the [111] SC Fe model. Irradiation leads to the increase of elastic modulus owing to the annihilation of irradiation point defects. However, the non-annihilable irradiation clusters reduced the strength. The decrease of yield strain and yield strength of the [111] SC Fe model is significantly higher than those of [110] and [100] SC Fe models, exhibiting worse radiation damage resistance. This is due to the number and types of operation of slip systems in the [110] and [100] SC Fe after irradiation, which is caused by its poor inhibition of [111] crystal orientation on clusters under irradiation, being much lower than those in the [111] SC Fe. The yield strength of SC Fe increases with the increase of the number and length of 1/2 (111) and (100) dislocations, while the plasticity decreases with the increase of the falling gradient of dislocations after yield. The purpose is to provide theoretical guidance for the microstructure design and regulation of radiation-damage-resistant iron-based materials.