Simulation Study on Edge Dislocation Motion and Its Interaction with Dislocation Loop in Pure V and TiVTa Alloy
Authors: Wang shumin  , He Xinfu  , Dou Yankun  ,   1 Reactor Engineering Technology Research Institute, China Institute of Atomic Energy, Beijing 102413, China
Published: February 2025

In this paper, the motion of edge dislocations and the interaction between edge dislocations and dislocation loops in pure V and TiVTa alloy were simulated. The aim was to reveal the influence of the existence of <111> dislocation loops, which are dominant in pure V, and <100> dislocation loops, which are dominant in TiVTa alloy, on the irradiation properties of materials and the differences between the irradiation properties influenced by the two types of dislocation loops. Edge dislocations and <100> loops and <111> loops with different sizes were introduced into pure V and TiVTa alloy using molecular dynamics simulation technology. The effects of loop type, loop size, and temperature on the interaction between edge dislocations and dislocation loops in pure V and TiVTa alloy were compared and analyzed. The differences in the interaction between dislocations and dislocation loops were summarized, and the reasons were revealed.<br>The simulation results of edge dislocation motion revealed that the velocity of edge dislocations in pure V decreases with increasing temperature, while the velocity of edge dislocations in TiVTa alloy showed no obvious correlation with temperature. This is because in pure V, the motion of edge dislocations is controlled by the phonon resistance mechanism. In TiVTa alloy, due to inevitable local chemical fluctuations, the phonon resistance mechanism and the nanoscale segment detrapping mechanism simultaneously control the motion of edge dislocations.<br>The simulation results of the interaction between edge dislocations and dislocation loops showed that there are two kinds of interaction mechanisms between dislocations and loops in pure V and TiVTa alloy: for small dislocation loops, dislocations tend to absorb the loops and continue to move; for large dislocation loops, dislocations tend to cut through the loops and then move forward. With the increase in the size of dislocation loops, the stress required for dislocations to break away from the dislocation loops also increases. With the increase in temperature, the stress required for dislocations to break away from the dislocation loops decreases. This is because the larger the size of the loops, the larger the contact area between dislocations and loops, and the greater the obstacle presented by the loops. With the increase in temperature, atomic vibrations are accelerated, and the hindrance of the loops is reduced.<br>When comparing the interaction between <100> loops and <111> loops and dislocations, it is found that the hindrance of <111> loops to dislocation movement is lower than that of <100> loops, and the difference in the hindrance of <100> loops and <111> loops to dislocations is more obvious in pure V than in TiVTa alloy. This is because the mobility of <111> loops is higher than that of <100> loops, so the hindrance of <111> loops to dislocation motion is lower than that of <100> loops. However, in TiVTa alloy, significant lattice distortion reduces the mobility of <111> loops. Therefore, compared with pure V, in TiVTa alloy, although the hindrance of <111> loops is lower than that of <100> loops, the difference between them is reduced.