Atomistic Simulations of Particle Reinforced Nanocrystalline Materials

Nanocrystalline materials have applications in numerous fields due to their high strength. Grain growth is prevalent in nanocrystalline materials and leads to a decrease in material strength. Zener pinning has proven to be effective in hindering grain growth and thus, maintain the strength of the material. In this work, atomistic simulations were performed to understand and visualize the effect of Zener pinning in restricting grain boundary motion, and hence grain growth. The simulations were performed on two different grain boundary structures, ∑ 5 and ∑ 17 by varying the particle diameter and distance between the particles and compare these results with that of structures without any particles. The impact of adding high particle volume fraction (up to 50%) in Ag polycrystals to produce ultrahigh strength materials is also discussed. The yield strength of these nanocomposites was evaluated by varying particle volume fraction, particle size and inter-particle spacing. The highest yield strength observed in Ag nanocomposites was found to be about 5 times the strength of nanocrystalline Ag. The possible strengthening mechanisms responsible for this huge increase are discussed based on molecular dynamics results.