Alloy: Difference between revisions
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! “Coin electrum” (d20) | ! “Coin electrum” (d20) | ||
| 906 fine electrum | | 906 fine electrum | ||
| {{frac|29|72}} Au, {{frac|145|288}} Ag, {{frac|3|32}} Cu | | {{frac|25|64}} Au, {{frac|33|64}} Ag, {{frac|3|32}} Cu <!-- {{frac|29|72}} Au, {{frac|145|288}} Ag, {{frac|3|32}} Cu --> | ||
| 𝜌 = {{alloy|Au= | | 𝜌 = {{alloy|Au=25/64|Ag=33/64|Cu=3/32}} | ||
|- | |- | ||
! “Coin silver” (d20) | ! “Coin silver” (d20) | ||
| Line 43: | Line 43: | ||
! “Coin copper” (d20) | ! “Coin copper” (d20) | ||
| 906 fine copper | | 906 fine copper | ||
| {{frac|29|32}} copper, {{frac|3|32}} | | {{frac|29|32}} copper, {{frac|3|32}} tin/zinc | ||
| 𝜌 = | | 𝜌 = {{alloy|Cu=29/32|tin=3/64|zinc=3/64}} | ||
|} | |} | ||
Revision as of 21:33, 29 October 2018
An alloy is a combination of metals or of metals and other elements.
Examples
- Crown gold
- A 22 karat (kt) (916 2⁄3 fine) gold alloy used for English & UK gold coins from 1526 (Henry VIII) to 1914 (as currency), and since then for trade and bullion coins. (22⁄24 gold, 2⁄24 copper)
- 𝜌 = 17.61 g/㎝³
- “Standard gold” (US)
- A 900 fine gold alloy used for US coins. (90% gold, ≤5% silver, 5-10% copper)
- 𝜌 = 17.43±.12 g/㎝³
- “Crown electrum” (d20)
- A 4 ℥ 17 3⁄4 ʤ gold, 6 ℥ 3½ ʤ silver, 18 3⁄4 ʤ copper alloy worth 1⁄2 of crown gold by weight (presuming that sterling silver is worth 1⁄10 of crown gold by weight). (i.e. the d20 gold-silver standard)
- Britannia silver
- An 11 ℥ 10 ʤ (958 fine) silver alloy required in England for “wrought plate” (non-monetary silversmithing) from 1697–1720 to inhibit coin clipping and melting. (23⁄24 silver, 1⁄24 copper)
- 𝜌 = 10.42 g/㎝³
- Sterling silver
- An 11 ℥ 2 1⁄4 ʤ (926 fine) fine silver alloy used for English & UK silver coins from before 1158 (Henry II) to 1919. (92.6% silver, 7.4% copper)
- 𝜌 = 10.37 g/㎝³
- “Standard silver” (US)
- A 900 fine silver alloy used for US coins from ____ to 1964. (90% silver, 10% copper)
- 𝜌 = 10.32 g/㎝³
| “Coin gold” (d20) | 906 fine gold | 29⁄32 gold, 3⁄32 copper | 𝜌 = 17.42 |
|---|---|---|---|
| “Coin electrum” (d20) | 906 fine electrum | 25⁄64 Au, 33⁄64 Ag, 3⁄32 Cu | 𝜌 = 12.53 |
| “Coin silver” (d20) | 906 fine silver | 29⁄32 silver, 3⁄32 copper | 𝜌 = 10.33 |
| “Coin copper” (d20) | 906 fine copper | 29⁄32 copper, 3⁄32 tin/zinc | 𝜌 = 8.76 |
Density
- ᴍ = material constituent
- 𝜌 = density (i.e. g/㎝³)
- 𝐴ᵣ = atomic weight
- 𝑤 = mass fraction (i.e. 9⁄10, .900 or 90%)
- 𝑎𝑡٪ = atomic percent
- Alloy (general)
| 𝜌Alloy | = | 1 | |||||||||||
|
- Au-Ag
- 𝜌Au-Ag = 𝜌Au 𝑤Au + 𝜌Ag 𝑤Ag − 4 exp(0.005 𝑤Au) 𝑤Au 𝑤Ag
- Au-Cu
- 𝜌Au-Cu = 𝜌Au 𝑤Au + 𝜌Cu 𝑤Cu − 5 exp(0.01 𝑤Au) 𝑤Au 𝑤Cu
- Ag-Cu
- 𝜌Ag-Cu = 𝜌Ag 𝑤Ag + 𝜌Cu 𝑤Cu − 0.12 exp(0.02 𝑤Cu) 𝑤Ag 𝑤Cu
- Au-Ag-Cu
- 𝜌Au-Ag-Cu = 1.004 𝑎𝑡٪Au 𝜌Au + 1.03 𝑎𝑡٪Ag 𝜌Ag + 0.096 𝑎𝑡٪Cu 𝜌Cu + x − y
- x = 0.35 ( cos(45+0.45 𝑎𝑡٪Au) + cos(45+0.45 𝑎𝑡٪Ag) + sin(𝑎𝑡٪Au) )
- y = 0.005 (𝑎𝑡٪Au+𝑎𝑡٪Ag) cos(0.9 𝑎𝑡٪Cu) + 0.2 cos(3.2 𝑎𝑡٪Cu)
-
𝑎𝑡٪ᴍ₁ = 𝑤ᴍ₁ 𝐴ᵣᴍ₁ 𝑤ᴍ₁ 𝐴ᵣᴍ₁ + 𝑤ᴍ₂ 𝐴ᵣᴍ₂ + 𝑤ᴍ₃ 𝐴ᵣᴍ₃ + ⋯
References
- Kraut, J.C.; Stern, W.B. (June 2000) “The Density of Gold-Silver-Copper Alloys and its Calculation from the Chemical Composition”. Gold Bulletin, Vol. 33, Iss. 2, pp. 52–55. Springer-Verlag. doi:https://doi.org/10.1007/BF03216580.