Molecular Dynamics Simulation Study of Ultrasonic Powder Consolidation Process

An Ultrasonic Powder Consolidation is an additive manufacturing technique that utilizes high-frequency vibrations to consolidate micro/nano powder materials to fully dense and near to net-shaped parts. Unlike traditional powder consolidation techniques such as sintering, shock wave-based and pressure-based processes, the consolidation during Ultrasonic Powder Consolidation process happens at relatively low temperatures and pressures within few seconds or less. Ultrasonic Powder Consolidation process presents several inherent advantages including low power consumption, low cost and zero thermal stresses on the consolidated parts. Experimental studies have shown that Ultrasonic Powder Consolidation process is capable of successfully consolidating powders of metals and metal-matrix composites. While Ultrasonic Powder Consolidation process promises several potential applications, the mechanism of bond formation between the consolidated metal powders is not completely understood. This research uses Molecular Dynamics simulation technique to investigate the underlying bond formation and consolidation mechanisms involved in Ultrasonic Powder Consolidation process. The research also explores the effects of critical process parameters including vibration frequency, amplitude and initial temperature on the quality of the consolidated part. The study found that high-frequency vibrations cause high interfacial stresses resulting in acoustic softening and high plastic deformation of the nanoparticles. The study revealed that the overall atomistic temperature does not exceed the melting point of the material. The study also found that the vibration amplitude and frequency played a significant role in the consolidation process. Finally, the simulation study showed that the high-frequency vibration leads to large plastic deformations at ultra-high shear strain rates causing the interfacial atoms to interlock with each other resulting in high densification and consolidation. The results of this study would augment the ongoing experimental studies on Ultrasonic Powder Consolidation process which would help realize the promised potentials of this low temperature – low-pressure consolidation technique.