Atomic Research on the Diffusion Behavior, Mechanical Properties and Fracture Mechanism of Fe/Cu Solid–Liquid Interface

A molecular dynamics simulation was applied to investigate the diffusion behavior and mechanical properties of a Fe/Cu solid–liquid interface with different orientations, temperatures, and strain rates. The results show that the displacement distance of Fe atoms’ diffusion into the Cu matrix was obviously larger than that of Cu atoms’ diffusion into the Fe matrix at any diffusion temperature and diffusion time. Moreover, the diffusion coefficient and diffusion distance both increase with temperature and time, and reach the highest value when the temperature and diffusion time are 1523 K and 3 ns, respectively. Additionally, the diffusion coefficients of the Fe atoms are arranged in the following order: Fe (100) < Fe (110) < Fe (111). The diffusion coefficients of the Cu atoms are arranged in the following order: Cu (110) > Cu (111) > Cu (100), when temperature and time are 1523 K and 3 ns, respectively. The yield strength and fracture strain of the bimetallic interface is positively correlated with the strain rate, but negatively correlated with the tensile temperature. Moreover, the yield strength of the three orientations can be arranged as follows: Fe (110)/Cu (110) > Fe (100)/Cu (100) > Fe (111)/Cu (111), and the yield strength and fracture strain of Fe (110)/Cu (110) diffusion interface are 12.1 GPa and 21% when the strain rate was 1 × 109/s and the tensile temperature was 300 K. The number of stacking faults and dislocations of the diffused Fe/Cu interface decreased significantly in comparison to the undiffused Fe/Cu interface, even in the length of Stair-rod dislocation and Shockley dislocation. All these results lead to a decrease in the tensile yield strength after interface diffusion.