Simulation studies are done to understand the role of dopants that segregate preferentially to grain boundaries on the stability of nanocrystalline aluminum. A dopant design framework based on thermodynamic principles, is used to identify the specific dopant type with the highest potential to segregate to grain boundaries in nanocrystalline aluminum. Various elements are evaluated as potential dopants and magnesium is identified to have the highest tendency to segregate to grain boundaries and release the excess free energyleading to the relaxation of the grain boundaries. A systematic combination of atomic structure analysis is then done to correlate grain boundary relaxation and the mechanical response of the magnesium-doped nanocrystalline aluminum at ambient temperature. The atomistic simulations reveal that the preferential partitioning of magnesium dopants to the grain boundaries reduces the excess volume within this region which stabilizes the nanostructure. At low contents, the magnesium dopants are observed initially partition to the grain boundaries, but once saturation of the grain boundaries is reached, excess dopants are accommodated in the crystalline interiors. It is found that the addition of the magnesium dopants even in the dilute limit, enhances the strength of the nanocrystalline aluminum. The formation of large, disordered GBs in doped nanocrystalline aluminum under tensile load allowed it to accommodate the deformation and prohibit crack growth.

进行模拟研究以了解优先偏析到晶界的掺杂剂对纳米晶铝稳定性的作用。基于热力学原理的掺杂剂设计框架用于识别在纳米晶铝中最有可能分离到晶界的特定掺杂剂类型。各种元素被评估为潜在的掺杂剂，并且镁被认为具有最高的偏析到晶界并释放导致晶界松弛的过量自由能的趋势。然后进行原子结构分析的系统组合，以关联晶界弛豫和镁掺杂纳米晶铝在环境温度下的机械响应。原子模拟表明，镁掺杂剂优先分配到晶界减少了该区域内的多余体积，从而稳定了纳米结构。在低含量下，观察到镁掺杂剂最初分配到晶界，但一旦达到晶界饱和，多余的掺杂剂就会容纳在晶体内部。发现即使在稀释限度内添加镁掺杂剂，也提高了纳米晶铝的强度。在拉伸载荷下，掺杂纳米晶铝中大而无序的 GB 的形成使其能够适应变形并阻止裂纹扩展。观察到镁掺杂剂最初分配到晶界，但一旦达到晶界饱和，多余的掺杂剂就会被容纳在晶体内部。发现即使在稀释限度内添加镁掺杂剂，也提高了纳米晶铝的强度。在拉伸载荷下，掺杂纳米晶铝中大而无序的 GB 的形成使其能够适应变形并阻止裂纹扩展。观察到镁掺杂剂最初分配到晶界，但一旦达到晶界饱和，多余的掺杂剂就会被容纳在晶体内部。发现即使在稀释限度内添加镁掺杂剂，也提高了纳米晶铝的强度。在拉伸载荷下，掺杂纳米晶铝中大而无序的 GB 的形成使其能够适应变形并阻止裂纹扩展。