Abstract In this paper, the uniaxial cold compaction process of metal nano-powders is numerically analyzed through the Molecular Dynamics (MD) method. The nano-powders consist of nickel and aluminum nano-particles in the pure and mixed forms with distinctive contributions. The numerical simulation is performed using the different number of nano-particles, mixing ratios of Ni and Al nano-particles, compaction velocities, and ambient temperatures in the canonical ensemble until the full-dense condition is achieved. In the MD analysis, the inter-atomic interaction between metal nano-particles is modeled by the many-body EAM potential, and the interaction between frictionless rigid die-walls and metal nano-particles is modeled by the pairwise Lennard-Jones inter-atomic potential. The mechanical behavior of metal nano-powders under the compaction process is numerically studied by plotting the relative density–pressure, mean stress-strain, and material characteristics–strain curves. Moreover, the nano-powder behavior is visualized by means of the centro-symmetry contour at various stages of the forming process. Finally, the evolution of top-punch velocity on the final stage of compaction process is studied by plotting the compaction pressure against the total energy at various compaction velocities.

中文翻译：

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结晶纳米粉体在冷压过程中的压实模拟与分子动力学分析

摘要 本文采用分子动力学(MD)方法对金属纳米粉体的单轴冷压成型过程进行了数值分析。纳米粉末由纯镍和铝纳米颗粒组成，具有独特的贡献。数值模拟是使用不同数量的纳米粒子、Ni 和 Al 纳米粒子的混合比、压实速度和标准系综中的环境温度进行的，直到达到完全致密的条件。在MD分析中，金属纳米粒子之间的原子间相互作用由多体EAM势建模，无摩擦刚性模具壁与金属纳米粒子之间的相互作用由成对Lennard-Jones原子间相互作用建模潜在的。通过绘制相对密度-压力、平均应力-应变和材料特性-应变曲线，对压实过程下金属纳米粉末的力学行为进行了数值研究。此外，纳米粉末的行为通过成型过程各个阶段的中心对称轮廓进行可视化。最后，通过绘制压实压力与不同压实速度下总能量的关系图，研究了压实过程最后阶段顶冲速度的演变。