ABSTRACT

The evolution of microstructure and the variation of strain field induced by precipitation in Al–Si–Mg–Cu alloy with high copper content during early ageing is characterised by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and geometric phase analysis (GPA) calculations. The basic building blocks for GP zones and step-shaped edges around subsequent precipitation are characterised. Incorporation of solute atoms, namely Si, Mg and Cu, accounts for the expansion of GP zones with core–shell structure and further precipitation transformation. The induced strain field rises as the ageing time increases and structural transformation proceeds, which results in a hardening of the sample.

摘要

高角环形暗场扫描透射电子显微镜（HAADF-STEM）和几何学表征了铜含量高的Al-Si-Mg-Cu合金在早期时效过程中的析出引起的微观结构演变和应变场变化。相位分析（GPA）计算。描绘了GP区域的基本构造块以及随后降水的阶梯形边缘。溶质原子（即Si，Mg和Cu）的结合说明了GP核壳结构的扩展以及进一步的沉淀转变。随着老化时间的增加和结构转变的进行，诱导的应变场增加，这导致样品硬化。