A cheap alloy for journal boxes and machinery may be made by substituting zinc for silver in the following atomic proportions:
| Cu | Al | Zn | |
|---|---|---|---|
| Zn + 2(Al + Cu6) = | 0.8643 | + 0.0622 | + 0.0734 |
| Zn + 2(Al + Cu9) = | 0.9053 | + 0.0435 | + 0.0512 |
| Zn + 2(Al +Cu12) = | 0.9273 | + 0.0333 | + 0.0394 |
This is subject to considerable shrinkage in casting, but is tenacious, and when drawn into wire has a tensile strength of ninety to one hundred thousand pounds.
The following alloys, in which iron enters as a third element, are well adapted for gun metal, being hard, tenacious, laminable, and ductile:
| Cu | Al | Fe | |
|---|---|---|---|
| Fe + (Al + Cu15) = | 0.9203 | + 0.0267 | + 0.0530 |
| Fe + (Al + Cu9) = | 0.9399 | + 0.0446 | + 0.0149 |
Also a four-element alloy of
| Cu | Al | Zn | Fe | ||
|---|---|---|---|---|---|
| 1. | Fe + Zn + (Al + Cu12) = | 0.8386. | + 0.0305. | + 0.0712. | + 0.0600 |
| 2.. | Fe + Zn + (Al + Cu15) = | 0.8666. | + 0.0249. | + 0.0588. | + 0.0496 |
The tensile strength of the above alloys as drawn wire is 82,000 pounds for the first, and 107,000 pounds for the second.
All of the alloys in which zinc or zinc and iron enter in place of silver, the color is affected and the luster diminished.
With nickel and platinum for the third element, we have: