Abstract The coherent strain caused by the different sizes of the nanoscale η' phases in Al–Zn–Mg–Cu alloys was investigated via scanning transmission electron microscopy and geometric phase analysis. It is found that after the η' phase precipitates, a coherent strain field is generated in the matrix and inside the precipitated phase. Such coherent strain field changes with the thickness of the η' phase. The tensile strain is mainly distributed in the 7-layers-thick η' phase, whereas the compressive strain mainly exists in the 11-layers-thick η' phase. The asymmetrically coherent compressive strains are present in the matrices around the 7-layers-thick and 11-layers-thick η' phases, and the corresponding maximum values of the compressive strains are 11.2% and 14.4%, respectively. The quantitative characterization of the coherent strain field induced by the nanoscale η' phase provides a valuable reference for the optimization of the mechanical properties of the Al–Zn–Mg–Cu alloy.

中文翻译：

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通过扫描透射电子显微镜研究 Al-Zn-Mg-Cu 合金中 η' 相的相干应变演化

摘要 通过扫描透射电子显微镜和几何相分析研究了Al-Zn-Mg-Cu合金中不同尺寸的纳米级η'相引起的相干应变。发现η'相析出后，在基体和析出相内部产生相干应变场。这种相干应变场随着 η' 相的厚度而变化。拉应变主要分布在7层厚的η'相中，而压应变主要分布在11层厚的η'相中。7 层厚和 11 层厚 η' 相周围的基体中存在不对称相干压应变，相应的压应变最大值分别为 11.2% 和 14.4%。