Relation between microstructural aspects of AA2024 and its corrosion behaviour investigated using AFM scanning potential technique
Relation between microstructural aspects of AA2024 and its corrosion behaviour investigated using AFM scanning potential technique
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DOI：
10.1016/s0010-938x(00)00002-0
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发表时间：
2000-11-01
影响因子：
8.3
通讯作者：
de Wit, JHW
中科院分区：
文献类型：
--
作者：
Campestrini, P;van Westing, EPM;de Wit, JHW
铝合金的微观组织对腐蚀行为有很大的影响。特别是，金属间颗粒在铝合金的耐腐蚀性中起着重要的作用，由于原电池的形成，它们可以引起局部腐蚀，如点蚀和剥落。金属间颗粒的形状、大小和化学成分取决于对铝合金进行的加工路线（热处理和成形）。在我们实验室最近的工作中发现，当2024铝合金经历较长的淬火延迟时间（均匀化处理后在空气中度过的时间）时，会析出贝壳状颗粒。它们的特点是地核和地表的化学成分不同。同时，AA2024的腐蚀机制由一般腐蚀变为局部腐蚀。因此，认为壳状颗粒增加了2024铝合金的点蚀敏感性。本文采用原子力显微镜（AFM）扫描电位技术测量了这些粒子的表面电位。壳型粒子在核和壳之间表现出较大的电势差，这导致了高度局域化的电流耦合。因此，壳状颗粒的形成大大降低了AA2024的抗点蚀性。(C) 2000 Elsevier Science Ltd.版权所有。
The microstructure of the aluminium alloys has a large influence on the corrosion behaviour. In particular, the intermetallic particles play an important role in the corrosion resistance of aluminium alloys and they can give rise to localized corrosion, such as pitting and exfoliation, because of the formation of galvanic cells. The shape, size and chemical composition of the intermetallic particles are determined by the processing route (heat treatment and forming) carried out on the aluminium alloy. In recent work in our lab, it was found [9] that when the 2024 aluminium alloy undergoes a long quench delay time (time spent in air after the homogenisation treatment) shell-shaped particles precipitate. These are characterized by differences in chemical composition between the core and the surface. Simultaneously, the corrosion mechanism of the AA2024 changes from general to localized. Therefore, it was thought that the shell-shaped particles increase the pitting susceptibility of the 2024 aluminium alloy. In the present work, the surface potential of these particles was measured by means of atomic force microscopy (AFM) scanning potential technique. The shell-shaped particles show a large difference in potential between the core and the shell, which results in a highly localized galvanic coupling. Therefore, the formation of shell-shaped particles largely lowers the resistance to pitting attack of the AA2024. (C) 2000 Elsevier Science Ltd. All rights reserved.