DoITPoMS

Full Record for Micrograph 25

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Micrograph no
25
Brief description
Fe, C 0.85 (wt%), hypereutectoid alloy
Keywords
allotriomorph Link to MATTER Glossary entry for allotriomorph, alloy Link to MATTER Glossary entry for alloy, carbon, cementite Link to MATTER Glossary entry for cementite, hypereutectoid Link to MATTER Glossary entry for hypereutectoid, iron, metal, steel Link to MATTER Glossary entry for steel
Categories
Metal or alloy
System
Fe-C-X   Link to phase diagram
Composition
Fe, C 0.85 (wt%)
Standard codes
Reaction
Processing
Furnace cooled from 1000 °C
Applications
Sample preparation
Etched in 2% nital
Technique
Reflected light microscopy
Length bar
400 μm
Further information
This is a hypereutectoid alloy and illustrates the effect of slow cooling rate on the resultant microstructure. The first phase to form from the melt is proeutectoid cementite. With slow cooling, furnace cooled, allotriomorph cementite forms on the prior austenite grain boundaries, rejecting iron into the melt. At the eutectoid composition the remaining austenite transforms to pearlite.
Contributor
Prof T W Clyne
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Date
25/10/01
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales
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