Study on the influence of dislocation dynamic characteristics in Fe-based Cr-Mo alloy at high temperature

Abstract The dislocation dynamics in Fe-based alloys are significantly different at high temperatures compared to room temperature. Due to the influence of solid solution atom segregation in the crystal, dislocation walls can easily form, leading to fine grain strengthening. This mechanism makes the study of dislocation dynamics in Fe-based alloys highly valuable for practical applications. To explore the influence of dislocation dynamics in Fe-based Cr-Mo alloys at high temperatures and under small strain conditions, the correlation between solid solution atom segregation and dislocation aggregation at different temperatures was investigated using the molecular dynamics (MD) method. Under the same strain, the dislocation dynamics are most significantly affected by solute atoms at temperatures around 603 K. At this temperature, the number of C and Cr atomic clusters increases with strain, while the number of Mo clusters decreases, indicating that this is the optimal temperature range for the formation of C and Cr clusters. In the analysis of the coupling effects of solute atoms, it was observed that at 603 K, C-Cr and C-Mo clusters exhibit distinct influences on dislocation dynamics. Cr atoms impede dislocation motion by forming stable structures, whereas Mo alters the energy barrier, which leads to the formation of a Cottrell atmosphere that hinders dislocation motion. The results of this study provide an effective theoretical basis for regulating Fe-based alloys to induce ultrafine grain characteristics.