## 3 Results and Discussion
### Influence of Multiple Interactions on the Structure of Inclusion and Stress State of the MD System
On the rim of inclusion, the dislocation segments are pulled out and get a screw character; after that, the cross-slip of these segments can take place (Figure 7, 470 ps). The consequence of these two processes is the situation when the dislocation separating from inclusion has a central segment located in the overlying slip plane, while other segments are located in the initial plane. Such a dislocation exit from the initial slip plane is accompanied by the formation of the extensive defect structure near inclusion besides the Orowan loop (Figure 7, 470 ps). The movement of dislocation with a segment in the adjacent slip plane is impeded in comparison with sliding in one plane due to the additional energy of the segments connecting the segments in the basic slip plane with the segments located in the adjacent plane. This state is metastable and after a while it spontaneously collapses. The return of the segment from overlying plane to base plane is accompanied by the generation of vacancies in the aluminum matrix (Figure 7, 490 ps) [78]. The volume fraction of vacancies in the system as a time function is shown in Figure 7b; the methodology for their calculation is given below in Section 3.3. Figure 6: View of \(\theta^{\prime}\) precipitate after several interactions with dislocation; interaction number is indicated above each view together with the corresponding time. Diameter of \(\theta^{\prime}\) phase is 5 nm; shear velocity is 5 m/s; and temperature is 300 K. Only copper atoms are shown. Figure 7: Time dependences of averaged shear stresses (**a**), volume fraction of vacancies (**b**) and position along the \(y\)-axis of dislocation for the system of 17.6 nm thickness at a temperature of 300 K. Atomic distributions corresponding to the times indicated on the graph are shown. Copper atoms are shown in red; aluminum atoms are in gray (only atoms with the centrosymmetry parameter exceeding 5 square angstroms are shown); green lines are Shockley partial dislocation segments; blue lines are perfect dislocation segments; black lines are vertex dislocation segments. Since the absorption and emission of vacancies by dislocation is attended by the exit of segments from the initial slip plane of dislocation, and the quantity accumulated in system vacancies is large, the exit of whole dislocation from the slip plane occurs with time. Moreover, both the displacement into the underlying slip plane with the vacancy emission and the displacement into the overlying plane are possible. In the latter case, the displacement is stimulated by the dislocation interaction with the obstacle and the transverse slip of the screw dislocation segments on it, and leads to the subsequent absorption of vacancies accumulated in the bulk of aluminum. Figure 7 shows the time dependence of the average position of all dislocation segments in the system along the \(y\)-axis. Dislocation segments are determined using the DXA. Note that with increasing deformation in the system, stable vertex dislocation segments are formed, as shown in Figure 7 (2780 ps) as lilac segments. The presence of such segments makes the position of the mobile dislocation found by averaging all the segment coordinates, which is less accurate, but this information is sufficient for a qualitative analysis. Joint consideration of the dependences of the average stresses in the region, the vertical position of the dislocation and the number of vacancies allows us to draw the following conclusions. Sequential passage of a dislocation through the inclusion in one slip plane leads to a violation of inclusion structure, which provokes the diminution in the resistance to dislocation movement. On the graph of stress versus time, a tendency to diminution in stress in the region is observed. The dependence of the position of dislocation along the \(y\)-axis shows the areas of active displacement of segments from one slip plane to another (Figure 7); these periods are in good agreement with the periods of accumulation of vacancies in the region (Figure 7b).