Simulation study on edge dislocation motion and its interaction with dislocation loop in pure V and TiVTa alloy

SM Wang and XF He and YK Dou, ACTA PHYSICA SINICA, 74, 078101 (2025).

DOI: 10.7498/aps.74.20241757

The motion of edge dislocations and the interaction between edge dislocations and dislocation loops in pure V and TiVTa alloy are simulated in this work, with the aim to reveal the influences 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. The edge dislocations and < 100 > loops and < 111 > loops with different sizes are introduced into pure V and TiVTa alloy by 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 are compared with each other and analyzed. The differences in interaction between dislocations and dislocation loops are summarized, and the reasons are revealed.
The simulation results of edge dislocation motion reveal that the velocity of edge dislocations in the pure V decreases with temperature increasing, while the velocity of edge dislocations in the TiVTa alloy shows no significant relation to temperature. This is due to phonon-drag mechanism controlling the motion of edge dislocations in the pure V. In the TiVTa alloy, due to inevitable local chemical fluctuations, the phonon-drag mechanism and the nanoscale segment detrapping mechanism simultaneously control the motion of edge dislocations.
The simulation results of the interaction between edge dislocations and dislocation loops show 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 go through the loops and then move forward. With the size of dislocation loop increasing, the stress required for dislocations to detach from the dislocation loops also increases. With the increase of temperature, the stress required for dislocations to detach 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.
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 to dislocation between < 100 > loops and < 111 > loops is more significant in pure V than what is observed in TiVTa alloy. This is because the mobility of < 111 > loops is higher than that of < 100 > loops, the hindrance to dislocation motion of < 111 > loops is lower than that of < 100 > loops. However, in the TiVTa alloy, significant lattice distortion reduces the mobility of < 111 > loops. Therefore, the hindrance of < 111 > loops in the TiVTa alloy is lower than that of < 100 > loops, but the difference between them is reduced compared with what is observed in pure V.
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