Abstract A novel stress-strain relation with two stages of linear elastic deformation is observed in [001]-oriented tetragonal zirconia nanopillars subjected to tensile loading via molecular dynamics simulation. This phenomenon results from a phase transformation from the tetragonal structure to the monoclinic one. Detailed explorations including the crystallographic structural analysis and the atomic strain calculation have been made to further elucidate the stress-strain curve. The lattice orientation strongly affects the plastic deformation mechanism, i.e., the [001]- and [011]-oriented nanopillars experience the phase transformation under tensile loading, while the brittle fracture is induced for the orientation lying along the [111] direction. Complementary uniaxial compressive tests are performed to study the loading direction dependence. The deformation mechanism differs for the nanopillars with the same lattice orientation but different loading directions; for instance, under compressive loading, the plastic deformation behavior for [001]-oriented nanopillar is governed by intense dislocation activity rather than phase transformation. Additionally, a significant temperature effect is observed, with Young's modulus decreasing linearly from 323.97 to 283.55 GPa as the temperature increases from 300 to 1400 K. This work will help deepen the understanding of the tetragonal-to-monoclinic transformation and nanoscale mechanical behavior of zirconia.

中文翻译：

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四方氧化锆纳米柱在单轴加载下的力学行为：分子动力学研究

摘要 通过分子动力学模拟，在承受拉伸载荷的 [001] 取向四方氧化锆纳米柱中观察到了具有两阶段线弹性变形的新型应力-应变关系。这种现象是由于从四方结构到单斜结构的相变所致。为了进一步阐明应力-应变曲线，进行了包括晶体结构分析和原子应变计算在内的详细探索。晶格取向强烈影响塑性变形机制，即[001]-和[011]-取向的纳米柱在拉伸载荷下经历相变，而沿[111]方向的取向诱导脆性断裂。进行补充单轴压缩试验以研究加载方向的相关性。晶格取向相同但加载方向不同的纳米柱变形机制不同；例如，在压缩载荷下，[001] 取向纳米柱的塑性变形行为受强烈位错活动而不是相变控制。此外，观察到显着的温度效应，随着温度从 300 增加到 1400 K，杨氏模量从 323.97 GPa 线性下降到 283.55 GPa。这项工作将有助于加深对氧化锆的四方到单斜相转变和纳米级力学行为的理解. [001] 取向纳米柱的塑性变形行为受强位错活动而不是相变控制。此外，观察到显着的温度效应，随着温度从 300 增加到 1400 K，杨氏模量从 323.97 GPa 线性下降到 283.55 GPa。这项工作将有助于加深对氧化锆的四方到单斜相转变和纳米级力学行为的理解. [001] 取向纳米柱的塑性变形行为受强位错活动而不是相变控制。此外，观察到显着的温度效应，随着温度从 300 增加到 1400 K，杨氏模量从 323.97 GPa 线性下降到 283.55 GPa。这项工作将有助于加深对氧化锆的四方到单斜相转变和纳米级力学行为的理解.