Image icon  Wrought-grade aluminium alloy

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Description: The micrograph shows Al-Mg-Fe-Si containing < 1wt.% of each solute; refined with TiB2 particles. Deformation of grain structure is due to cutting of sample with scissors. This micrograph illustrates the effect of deformation on a previously equiaxed structure. Strain causes the elongation of grains and the subsequent anodising produces 'mottled' grain colours; the oxide layer is not of constant orientation or thickness across a grain.

The Barker's etch and applied electrical field produce 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 and oxide thickness; hence the grain structure is imaged.
Keywords: alloy • aluminium • anodising • deformation • equiaxed • iron • magnesium • metal • silicon
Categories: Science approaches > Microstructure
Materials > Metals & alloys > Aluminium & alloys
Testing, analysis & experimentation > Metallography
Scale > Micro
Created by: DoITPoMS, University of Cambridge
T Quested, Department of Materials Science and Metallurgy, University of Cambridge
Published by: DoITPoMS, University of Cambridge
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Date created: 20 January 2003
Date added: 21 August 2009
Resource ID: 1739