Grain Boundary Motion in Magnetic-Pulse-Welded Al-Fe Bimetal Systems: An Atomistic Simulation Study

Abstract

Magnetic pulse welding (MPW) is an ef ective solid-state welding method of joining dissimilar metals such as Al/Steel, Al/Ti, Al/Cu et al. In order to understand fully such important phenomena as atomic dif usion, grain boundary motion, interfacial non- equilibrium-phase nucleation and growth in MPW, a detailed microscopic description of the MPW interface is necessary. This study is an extension of our previous work. In the present work, we extend the simulation investigation to polycrystal aluminium and iron systems using Molecular dynamic (MD) method. The polycrystal systems allow for the study of interfacial segregation. Our simulations present structural information on the GBs in nanocrystalline microstructures. Flat GBs can move when subjected dynamic load resulting from the high-velocity impact. Plots of the ratio of GB atoms versus time show a distinctly dif erent GB migration behaviors between loading and unloading conditions. By contrast with our earlier simulations, it was observed that crystal order and stability are highly preserved in the loading stage. The transformation of grain boundary structural change is due to stress-driven GB migration and temperature dependent as well. Grain rotation mechanism was identified. This work could provide atomistic insights into the grain refinement during MPW process.