Abstract The deformation behavior, the fracture mechanism, and the mechanical properties of the Cu/Ta nanoscale metallic multilayers (NMMs) with the vertical and horizontal layers under the tension process are meticulously studied using molecular dynamics (MD) simulations. The influences of the various temperatures, strain rates and modulation periods (λ) are evaluated in detail through the dynamic responses, the stress-strain relationships, and the dislocation density diagrams of the Cu/Ta NMMs. The results reveal that the phase transitions from the FCC structures into the HCP, BCC, and amorphous structures mainly occur in the Cu layers. Only a small amount of the BCC structures transforms into the amorphous structures in the Ta layers. In the Cu layers, the 〈1 1 2〉 and 〈1 1 0〉 dislocations are mostly formed, while the 〈1 1 1〉 dislocations are mostly found in the Ta layers. The defects occur in the interface and then extend towards the Cu layers for the vertical layers specimens. For the horizontal layers specimens, the defects appear both in the Ta layers and in the interface. The tensile strength of the vertical layers specimens is lower than that of the horizontal layers specimens under the same testing conditions. As increasing temperature, the tensile strength and the dislocation density reduce. However, the tensile strength and the dislocation density increase with an increase in strain rate. The tensile strength slightly changes with the different λ. The dislocation density is higher with a larger λ.

中文翻译：

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Cu/Ta多层膜的相变和界面断裂：分子动力学研究

摘要 利用分子动力学 (MD) 模拟，仔细研究了在拉伸过程中具有垂直和水平层的 Cu/Ta 纳米级金属多层 (NMM) 的变形行为、断裂机制和机械性能。通过 Cu/Ta NMM 的动态响应、应力-应变关系和位错密度图详细评估了各种温度、应变率和调制周期 (λ) 的影响。结果表明，从 FCC 结构到 HCP、BCC 和非晶结构的相变主要发生在 Cu 层中。只有少量 BCC 结构转变为 Ta 层中的非晶结构。在Cu层中，主要形成<1 1 2>和<1 1 0>位错，而〈1 1 1〉位错主要存在于Ta层中。缺陷出现在界面中，然后向垂直层样品的 Cu 层延伸。对于水平层试样，缺陷出现在 Ta 层和界面中。在相同的试验条件下，垂直层试样的拉伸强度低于水平层试样的拉伸强度。随着温度升高，拉伸强度和位错密度降低。然而，拉伸强度和位错密度随着应变速率的增加而增加。抗拉强度随λ的不同而略有变化。λ 越大，位错密度越高。对于水平层试样，缺陷出现在 Ta 层和界面中。在相同的试验条件下，垂直层试样的拉伸强度低于水平层试样的拉伸强度。随着温度升高，拉伸强度和位错密度降低。然而，拉伸强度和位错密度随着应变速率的增加而增加。抗拉强度随λ的不同而略有变化。λ 越大，位错密度越高。对于水平层试样，缺陷出现在 Ta 层和界面中。在相同的试验条件下，垂直层试样的拉伸强度低于水平层试样的拉伸强度。随着温度升高，拉伸强度和位错密度降低。然而，拉伸强度和位错密度随着应变速率的增加而增加。抗拉强度随λ的不同而略有变化。λ 越大，位错密度越高。然而，拉伸强度和位错密度随着应变速率的增加而增加。抗拉强度随λ的不同而略有变化。λ 越大，位错密度越高。然而，拉伸强度和位错密度随着应变速率的增加而增加。抗拉强度随λ的不同而略有变化。λ 越大，位错密度越高。