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Processing of Bulk Nanocrystalline Metals at the US Army Research Laboratory
Published on: March 7, 2018
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Shock-Induced Microstructural Evolution, Phase Transformation, Sintering of Al-Ni Dissimilar Nanoparticles: A
Summary
Molecular dynamic simulations reveal distinct sintering mechanisms for Al-Ni nanoparticles under impact. Low-velocity impacts favor aluminum dislocation slip, while high-velocity impacts involve nickel dislocation slip and aluminum atomic diffusion.
Area of Science:
- Materials Science
- Nanotechnology
- Computational Physics
Background:
- Understanding nanoparticle interactions is crucial for designing advanced materials.
- The behavior of dissimilar nanoparticles under impact, particularly Al-Ni, requires detailed investigation.
Purpose of the Study:
- To explore the contact behavior, microstructure evolution, and sintering mechanisms of Al-Ni dissimilar nanoparticles under high-velocity impact.
- To compare simulation results with the Hertz model and identify deviations at increasing impact velocities.
Main Methods:
- Molecular dynamic simulations were employed to model the impact and sintering processes.
- The study analyzed contact stress, radius, and force, comparing them with Hertz model predictions.
Main Results:
- Simulations align with the Hertz model at low impact velocities but deviate at higher velocities due to elastic-plastic transitions and atomic discreteness.
- A weak dependence of normalized contact radius on nanosphere diameter was observed.
- Two distinct sintering mechanisms were identified based on impact velocity: dislocation slip in Al at low velocities, and combined Ni dislocation slip and Al atomic diffusion at high velocities.
Conclusions:
- The Hertz model is insufficient for describing Al-Ni nanoparticle impact at high velocities.
- Impact velocity significantly influences the dominant sintering mechanisms in Al-Ni nanoparticle systems.
