Al-Zn-Mg-Cu合金中一种新型Al_3Zr-η'核壳颗粒的透射电子显微镜观察（英文）

Transmission Electron Microscopic Observation of a Novel Al_3Zr-η' Core-shell Particle in Al-Zn-Mg-Cu Alloy

利用高分辨透射电子显微镜(HRTEM)和选区电子衍射(SAED)观察了Al-12Zn-2.4Mg-1.1Cu-0.5Ni-0.2Zr合金中的Al_3Zr-η′核壳颗粒。结果发现:Al_3Zr颗粒在合金基体中以2种形态存在,一种是与基体共格单独存在的Al_3Zr颗粒;另外一种是作为η′析出相形核位置的核心Al_3Zr颗粒,形成了一种与基体半共格的Al_3Zr-η′核壳颗粒。该核壳颗粒的壳层由4种η′析出相变体组成。核心Al_3Zr颗粒内部的晶格变形低于单独存在的Al_3Zr颗粒,η′析出相和基体界面处存在显著的晶格应变。

The Al3 Zr-η′ core-shell particles were observed in the Al-12 Zn-2.4 Mg-1.1 Cu-0.5 Ni-0.2 Zr alloy using high-resolution transmission electron microscopy(HRTEM) and selected area electron diffraction(SAED).Two types of Al3 Zr particles appear in the Al matrix:one is a standalone Al3 Zr particle that is coherent with the matrix,and the other is an as-core Al3 Zr particle acting as a nucleation site of the η′ precipitates,resulting in a core-shell particle which is semi-coherent with the matrix.The shell is composed of η′ precipitates with four variants.The strain in the as-core Al3 Zr is lower than that in the standalone Al3 Zr,and a considerable amount of strain exists across the interfacial regions between the η′ precipitates and the matrix.