Metallographic Etching of Al–Mg–Zn–(Cu) Crossover Alloys

Various alloys demand customized etchants due to their diverse chemical compositions, particularly in the realm of aluminum alloys. Consequently, in this study, a technique is proposed for metallographic visualization of small grain structures within Al–Mg–Zn–(Cu) crossover alloys. In this method, a...

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Bibliographic Details
Published in:	Advanced engineering materials Vol. 26; no. 19
Main Authors:	Samberger, Sebastian, Kremmer, Thomas, Stemper, Lukas, Tourey, Serena, Uggowitzer, Peter J., Pogatscher, Stefan
Format:	Journal Article
Language:	English
Published:	01-10-2024
Subjects:	aluminum alloys crossover alloys etching grain size measurements grain‐boundary precipitations light optical microscopies T‐phase
Online Access:	Get full text
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Summary:	Various alloys demand customized etchants due to their diverse chemical compositions, particularly in the realm of aluminum alloys. Consequently, in this study, a technique is proposed for metallographic visualization of small grain structures within Al–Mg–Zn–(Cu) crossover alloys. In this method, a thermal pretreatment combined with an etching process is relied on. In the study, it is primarily sought to comprehend how grain‐boundary precipitation affects etchability, addressing the complexities of characterizing these alloys. The demonstrated approach facilitates the swift assessment of grain sizes <10 μm using light optical microscopy. Exploring the etchability of Al–Mg–Zn–(Cu) crossover alloys across a standard heat‐treatment pathway identifies the optimal treatment and suitable etchant for grain visualization. Through process refinement, a reduction in processing time is achieved by employing a single‐step preheat treatment lasting 20 min at 180 °C post solution annealing. Transmission electron microscope analysis reveals continuous occupancy of the grain boundary with T‐phase as the key factor influencing the alloy's etchability. Grain size assessment involves line intercept counting and equivalent circle diameter measurement for precise characterization. A simple metallographic method in the form of a thermal pretreatment in combination with an established etching process enables a rapid evaluation of the grain size of Al–Mg–Zn–(Cu) crossover alloys. In this procedure, a continuous occupancy of the grain boundary with T‐phase is the key factor for the etchability of the alloy.
ISSN:	1438-1656 1527-2648
DOI:	10.1002/adem.202400576