The effects of doping ratio of calcium (Ca) on mechanical behaviors are investigated using molecular dynamics (MD) and the second nearest-neighbor modified embedded-atom method (2NN-MEAM) formalism for nanocrystalline (NC) Mg-Ca alloys system. Research results indicate that mechanical behaviors of Mg-Ca alloys are independent of lower strain rate (under 1.0 × 10⁹ s⁻¹). In addition, we observe that Ca doping can affect the mechanical properties of the Mg-Ca alloys, and the optimal 2.0 at% of Ca atoms, which has excellent plasticity, is revealed. When the doping ratio is lower than critical atomic percent (CAT) of Mg₂Ca, Young’s modulus and yield stress decrease increasing at% of substitutional Ca. The pyramidal <c + a > dislocations are observed frequently at more active grain boundary (GB) with higher Ca doping ratios. In contrast, with doping ratio above CAT, Mg₂Ca reinforcement dominates brittleness Mg/Mg₂Ca nanocomposites to obtain high strength. By calculating, a significant increase of strength is discovered when at% of Mg₂Ca is above 18.85 (5.34 at% Ca). Intergranular fractures are more likely to nucleate and propagate along weaker Mg/Mg₂Ca interfaces. These results are instrumental in design and improving the mechanical properties of Mg-Ca alloys.

中文翻译：

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Ca掺杂比对纳米晶Mg-Ca合金力学行为影响的原子学研究。

钙（Ca）掺杂比对力学行为的影响进行了研究，使用分子动力学（MD）和第二近邻修饰嵌入原子方法（2NN-MEAM）形式主义的纳米晶体（NC）Mg-Ca合金系统。研究结果表明，Mg-Ca合金的力学行为与较低的应变速率（在1.0×10 ⁹  s ^-1以下）无关。此外，我们观察到Ca掺杂会影响Mg-Ca合金的力学性能，并且揭示了具有出色可塑性的最佳2.0 at％的Ca原子。当掺杂比低于Mg _2的临界原子百分数（CAT）时Ca，杨氏模量和屈服应力随着替代Ca％的增加而降低。经常在具有较高Ca掺杂比的更活跃的晶界（GB）处观察到金字塔型<c + a>位错。相反，当掺杂比高于CAT时，Mg ₂ Ca增强剂控制脆性Mg / Mg ₂ Ca纳米复合材料以获得高强度。通过计算，发现当at％的Mg ₂ Ca高于18.85（5.34 at％Ca）时，强度会显着增加。晶间骨折更有可能沿着较弱的Mg / Mg ₂ Ca界面成核并扩展。这些结果有助于设计和改善Mg-Ca合金的机械性能。