Microstructure evolution mechanism of high entropy alloys under impact loading

In this article, molecular dynamics simulation method was used to establish a high entropy alloy atomic model, and different impact velocities were applied to study the impact induced high entropy alloy phase transformation and dislocation motion mechanism. It creatively reveals the evolution mechanism of thermal mechanical coupling response of FeCoCrCuNi high entropy alloy under impact loading. The results show that when the impact speed is higher than 1400 m/s, the temperature rise breaks through 5000 K under the impact, and the high entropy alloy particles become amorphous. When the impact speed reaches 1000 m/s, the atomic motion speed of Ni and Cu atoms is slightly increased compared to other elements, and the face-centered cubic (FCC) phase is largely transformed into hexagonal close-packed (HCP) phase, with the dislocation density reaching its peak. After passing through the wavefront, twinning is formed under the action of cross slip and dislocation reaction, which prevents further expansion of dislocations and forms a dislocation hollow area, enhancing the strength of localized materials.