Gao Feng, Yang Qi, Du Jiguang, Jiang Gang
Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China.
Key Laboratory of High Energy Density Physics and Technology, Ministry of Education, Chengdu, 610065, China.
J Mol Model. 2020 Apr 18;26(5):103. doi: 10.1007/s00894-020-04361-0.
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 × 10 s). 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 MgCa, 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, MgCa reinforcement dominates brittleness Mg/MgCa nanocomposites to obtain high strength. By calculating, a significant increase of strength is discovered when at% of MgCa is above 18.85 (5.34 at% Ca). Intergranular fractures are more likely to nucleate and propagate along weaker Mg/MgCa interfaces. These results are instrumental in design and improving the mechanical properties of Mg-Ca alloys.
采用分子动力学（MD）和第二近邻修正嵌入原子方法（2NN-MEAM）形式，研究了钙（Ca）掺杂比例对纳米晶（NC）Mg-Ca合金体系力学行为的影响。研究结果表明，Mg-Ca合金的力学行为与较低应变率（低于1.0×10⁻³ s⁻¹）无关。此外，我们观察到Ca掺杂会影响Mg-Ca合金的力学性能，并揭示了具有优异塑性的最佳Ca原子掺杂比例为2.0 at%。当掺杂比例低于MgCa的临界原子百分比（CAT）时，随着替代Ca的原子百分比增加，杨氏模量和屈服应力降低。在Ca掺杂比例较高的更活跃晶界（GB）处，经常观察到金字塔形<c + a>位错。相反，当掺杂比例高于CAT时，MgCa增强相主导脆性Mg/MgCa纳米复合材料以获得高强度。通过计算发现，当MgCa的原子百分比高于18.85（5.34 at% Ca）时，强度显著增加。沿晶断裂更有可能在较弱的Mg/MgCa界面处形核并扩展。这些结果有助于设计和改善Mg-Ca合金的力学性能。
