Eutectic Alloys.
—Lead-tin solders are eutectic alloys—that is, they are examples of the phenomenon of a combination of two metals melting at a temperature lower than one of them would if melted separately. Thus, lead melts at about 328° C., and tin at about 232° C., yet reference to the following table, given by Mr. A. H. Hiorns, will show that the “commonest” solder mentioned fuses at 303° C., and the “best” at 175° C.
Melting points of lead-tin alloys
| Tin % | Lead % | Melting point (C.) |
|---|---|---|
| 10 | 90 | 303° |
| 20 | 80 | 278° |
| 30 | 70 | 255° |
| 40 | 60 | 230° |
| 50 | 50 | 205° |
| 60 | 40 | 187° |
| 63 | 37 | 175° |
| 70 | 30 | 185° |
| 80 | 20 | 198° |
| 90 | 10 | 215° |