Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Micrograph 710 and full record

Micrograph 710 and full record

Link to image file for micrograph 710
Micrograph no
710
Brief description
Wrought-grade aluminium alloy (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.
Keywords
alloy Link to MATTER Glossary entry for alloy, aluminium Link to MATTER Glossary entry for aluminium, anodising Link to MATTER Glossary entry for anodising, deformation, equiaxed Link to MATTER Glossary entry for equiaxed, iron, magnesium, metal, silicon Link to MATTER Glossary entry for silicon
Categories
Metal or alloy
System
Al-Mg-Fe-Si
Composition
Not specified
Standard codes
Reaction
Processing
Deformed by cutting with scissors.
Applications
Sample preparation
Electrolytically etched using Barker's reagent.
Technique
Cross-polarised light microscopy
Length bar
400 μm
Further information
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.
Contributor
T Quested
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Date
20/01/03
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales
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