Image icon  Roll-bonded aluminium alloy diffusion couple in the as-rolled condition.

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Description: This micrograph shows the grain structure of a roll-bonded aluminium alloy diffusion couple in the as-rolled condition. The upper half of the couple is Al-0.5Fe-1.0Mn (wt.%), the lower half is Al-1.0Si (wt.%). Rolling heavily deforms the microstructure, producing thin, elongated grains parallel to the roll-bonded interface.

The Barker's etch produces a thick oxide layer on the grains of aluminium (anodising). When viewed in cross-polarised light, interference in the oxide layer produces colours which depend on grain orientation, hence the grain structure is imaged. Prior to roll-bonding the Al-Si alloy was solution-treated, creating recrystallized grains that were much larger than the cellular microstructure of the Al-Fe-Mn alloy. This difference in scale of microstructure can be seen in the rolled diffusion couple.
Keywords: alloy • aluminium • diffusion couple • metal • roll-bonding
Categories: Science approaches > Microstructure
Science approaches > Diffusion
Science approaches > Strengthening mechanisms > Recovery, recrystallisation & grain growth
Materials > Metals & alloys > Aluminium & alloys
Testing, analysis & experimentation > Metallography
Scale > Micro
Created by: DoITPoMS, University of Cambridge
D T L Alexander, Department of Materials Science and Metallurgy, University of Cambridge
Published by: DoITPoMS, University of Cambridge
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Date created: 21 May 2002
Date added: 21 August 2009
Resource ID: 1197