Molecular Dynamics Simulations of Atomic Diffusion during the Al–Cu Ultrasonic Welding Process

Abstract

Ultrasonic welding (UW) is an important joining technique in the electrical industry. Molecular dynamic simulation has been shown to possess several advantages for revealing the evolution of the atomic-scale structure and the interpretation of diffusion mechanisms at the microscopic level. However, voids associated with the understanding of microstructure evolution in the weld zone and dynamic processes that occur during ultrasonically welded materials still exist, and no UW studies at the atomic scale have so far been reported. In this study, molecular dynamic simulations of UW between Al and Cu were performed to investigate the diffusion behaviors of Al and Cu atoms. The results confirmed the occurrence of asymmetrical diffusion at the Al/Cu interface during UW. Meanwhile, recovery was noticed in the disordered Al blocks at low temperature. The thickness of the diffusion layer increased with the welding time. For relatively long welding times (1 ns), the concentrations of Al and Cu revealed the appearance of phase transitions. In addition, the diffusion during UW was identified as a dynamic and unsteady process. The diffusion coefficient was much larger than that underwent during the steady diffusion process despite the low interfacial temperature (below 375 K), which was mainly attributed to shear plastic deformation at the interface.

Molecular dynamics simulation of interface atomic diffusion in ultrasonic metal welding

“…8 Temperature evolution history dependent on the sliding velocity sliding velocity for each crystallite inclination angle. This is in good agreement with the results of the work by Yang et al [62], who introduced the diffusion process between dissimilar metals (Al and Cu) as a result of shear plastic deformations and not only the interfacial heat generation.…”

Ultrasonic Assisted Sintering Using Heat Converted from Mechanical Energy

“…As a result, diffusion coefficient can be increased by several orders of magnitude [44,45]. Besides, it is reported that volume diffusion can be further accelerated by the ultrasonic force field [46,47]. The much larger diffusion coefficient offers kinetic requirement for fast sintering.…”

Molecular dynamics simulation of atomic diffusion in friction stir spot welded Al to Cu joints

“…Since, in the present study, MD simulation has been carried out with scenario 1, wherein actual FSSW condition there will be no relative sliding motion will occur. The MD simulation of Al-Cu Jingwei et al, mentioned few non-FCC phases were formed during the ultrasonic welding, but their study on the non-FCC phases is not detailed further 17 . The current research focused on the interaction between Al and Cu materials atoms during FSSW condition in the solid-solid interface using numerical modelling and MD simulation for microanalysis.…”

“…The MD simulation has been carried out with scenario 1 because, in the actual FSSW condition, there will be no relative sliding motion between Al and Cu. Moreover, the study also focuses on the formation of non-FCC phases that have not been detailed in earlier literature 17 .…”