Full Record for Micrograph 697
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- Micrograph no
- 697
- Brief description
- Cu-4.5 wt% P
- Keywords
- alloy , bronze , copper, coring , dendrite , hypoeutectic , metal, phosphorus
- Categories
- Metal or alloy
- System
- Cu-P
- Composition
- Cu 95.5, P 4.5 (wt%)
- Standard codes
- Reaction
- Processing
- Applications
- This alloy has no practical applications
- Sample preparation
- Etch in ferric chloride
- Technique
- Reflected light microscopy
- Length bar
- 100 μm
- Further information
- This is an example of a hypoeutectic alloy. On slow cooling the liquid first solidified at approximately 940ºC as copper rich dendrites. The composition of the remaining liquid became increasingly rich in phosphorus until it solidified as a eutectic (8.38 wt% P) at the eutectic temperature of 714ºC. Note that the dendrites are cored - the different contrast after etching indicated that the composition varies with position in the dendrites. This is caused by non-equilibrium solidification. The cooling rate was too rapid for equilibrium to be maintained between the solid and the liquid phases.
This alloy has no practical applications. Phosphor bronzes usually contain 5 wt% Sn for solid solution strengthening with 0.2 wt% P for interstitial solution strengthening. They have high strength and corrosion resistance and are usually used for springs. - Contributor
- Dr J Marrow
- Organisation
- Department of Materials Science, University of Manchester and UMIST
- Date
- 07/11/02
- Licence for re-use
- Attribution-NonCommercial-ShareAlike 4.0 International
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