In situ transmission electron microscopy investigation of nucleation of GP zones under natural aging in Al-Zn-Mg alloy
In situ transmission electron microscopy investigation of nucleation of GP zones under natural aging in Al-Zn-Mg alloy
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DOI：
10.1016/j.scriptamat.2021.114319
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发表时间：
2021-10-07
影响因子：
6
通讯作者：
Misra, Amit
中科院分区：
文献类型：
--
作者：
Chatterjee, Arya;Qi, Liang;Misra, Amit
这项研究揭示了 Al-Zn-Mg 合金自然时效过程中的极早期（一小时内）沉淀可能具有非常复杂的过程，沉淀类型和形成机制具有强烈的波动。在透射电子显微镜内进行原位加热、淬火和随后的室温自然时效，以研究早期沉淀的形成和演变。研究表明，在非常早期的自然时效过程中，大约 2 分钟后溶质簇形成，随后与簇相邻的 GP-II 区在大约 10 分钟内成核。此外，发现 GP-II 的成核与 GP-I 相关，但不是以一种独特的机制。观察到 GP-I 沉淀物通过“分离”成核（即从 GP-I 和 Al 基质之间的界面）或通过原位成核（即从 GP-I 沉淀物）充当 GP-II 形成的位点。有时，观察到一些 GP-II 沉淀物溶解到 Al 基体中，而没有进一步转化为 eta' 沉淀物。由 Elsevier Ltd 代表 Acta Materialia Inc. 出版。
This investigation reveals very early-stage (within an hour) precipitation during natural-aging of Al-Zn-Mg alloy can have very complex processes with strong fluctuations in precipitate types and formation mechanisms. In situ heating followed by quenching and subsequent natural-aging at room temperature was carried inside transmission electron microscope to study the formation and evolution of early-stage precipitation. Investigation reveals formation of solute clusters at similar to 2 mins and subsequent nucleation of GP-II zone adjacent to clusters at similar to 10 mins during very early-stage natural-aging. Moreover, nucleation of GP-II is found to be related to GP-I but not in one unique mechanism. GP-I precipitates were observed to act as sites for the formation of GP-II either by 'separated' nucleation (i.e. from the interface between GP-I and Al matrix) or via in situ nucleation (i.e. from a GP-I precipitate). Occasionally, some GP-II precipitates were observed to dissolve into Al matrix without further transforming to eta' precipitates. Published by Elsevier Ltd on behalf of Acta Materialia Inc.