不同Mg/Si比的Al-Mg-Si-Zn合金析出相结构演变和时效硬化行为

Evolution of Precipitate Structure and Age-Hardening Behavior of Al-Mg-Si-Zn Alloys with Different Mg/Si Ratios

摘要:

利用力学性能测试、差示扫描量热分析及高角环形暗场成像扫描透射电镜技术研究了不同Mg/Si比的Al-Mg-Si-Zn合金在时效过程中的析出硬化行为。结果发现，Zn元素的添加对富Mg的Al-Mg-Si合金峰值时效硬度和屈服强度提升明显。Al-Mg-Si-Zn合金在时效过程中存在3条相向后期相（相或相）转变的路径，且富Mg合金更容易发生相向相的转变，而富Si合金则更倾向于发生相向相的转变。在早期和峰值时效阶段，Zn原子会占据析出相内部能量有利的原子位点。在过时效阶段，Zn原子会逐渐从析出相内部扩散并偏聚到析出相与Al基体的界面处。

Abstract:

The precipitation hardening behavior of Al-Mg-Si-Zn alloys with different Mg/Si ratios was studied by mechanical property test, differential scanning calorimetry, and high-angle annular dark-field scanning transmission electron microscope. The results show that the addition of Zn significantly increases the peak-aging hardness and yield strength of Mg-rich Al-Mg-Si alloys. There are three pathways for the transformation from the phase to the late-stage phases ( phase or phase) in Al-Mg-Si-Zn alloys during aging. The Mg-rich alloy is more likely to undergo transition from the phase to the phase, while the Si-rich alloy is more prone to experience transition from the phase to the phase. During the early and peak-aging stages, the Zn atoms enter the precipitates and occupy the energetically favorable atomic sites. During the over aging stage, the Zn atoms will gradually diffuse from the precipitate interior to the interface between the precipitates and the Al-matrix.