Abstract High resolution transmission electron microscopy (HRTEM) with nanometer-scaled energy-dispersive X-ray (EDX) was employed to investigate the transformation mechanisms of the GP zone → η′ → η precipitation sequence of AA7050, an Al-Zn-Mg-Cu alloy. Serial in-situ HRTEM frames revealed that separated nucleation of an η′ precipitate occurred elsewhere as the adjacent GPII zone dissolved. Evidence from HRTEM coupled with EDX showed that in-situ nucleation of a new η2 precipitate (one form of η) took place, wherein it gradually developed from the original η′ precipitate via a similar hexagonal structure with different compositions. The in-situ transition product was composed of two distinctive regions; one was identified as η′, and the other, as η.

中文翻译：

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AA7050铝合金分离形核和原位形核的透射电镜研究

摘要 采用纳米级能量色散 X 射线 (EDX) 高分辨率透射电子显微镜 (HRTEM) 研究了 AA7050 的 GP 区 → η' → η 析出序列的转变机制，Al-Zn-Mg-铜合金。系列原位 HRTEM 框架显示，当相邻的 GPII 区域溶解时，η' 沉淀物的分离成核发生在其他地方。来自 HRTEM 与 EDX 结合的证据表明，新的 η2 沉淀物（η 的一种形式）发生了原位成核，其中它通过具有不同成分的相似六方结构从原始 η' 沉淀物逐渐发展。原位过渡产物由两个不同的区域组成；一个被确定为 η'，另一个被确定为 η。