Notes on Fusible Alloys

Low-Melting-Point Alloys

"Fusible" just means "meltable", but the term has come to be used as "low melting point". Some of these alloys can be melted in hot water; all can be melted in a normal oven. Those listed here are made up of Bismuth, Lead, Tin, Cadmium, and/or Indium.

Bismuth is a heavy, white to pink, crystalline, brittle, highly diamagnetic, non-toxic lead-like metal. It is often used as a lead replacement in bullets and shot, and for casting. Interestingly, it has the second lowest thermal conductivity of any metal (mercury has the least). It goes for around $10 a pound.

Lead is a soft, malleable, ductile, bluish-white, dense, and toxic metal. The stuff in pencils is NOT lead. Lead goes for about $5 a pound.

Tin is a malleable, silvery metal, usually used for coating other metals to prevent corrosion. You probably knew that, but I betcha didn't know this: tin is the most tonally resonant of all metals, and is a superconducter under 3.72 Kelvin. About $5 a pound.

Cadmium is a soft, bluish-white metallic element, easily cut with a knife, and toxic. It is used in low-friction, fatigue-resistant alloys, solders, dental amalgams, nickel-cadmium storage batteries, nuclear reactor shields, and in rustproof electroplating. Costs around $2 a pound.

Indium is a very soft, malleable, silvery-white metal. Used in making electronic devices and mirrors. VERY expensive, up to $2000 a pound.

Bad Juju!

Lead and Cadmium are cumulative poisons, meaning they build up in your system and kill you nice and slow. Read the Manufacturer Safety Data Sheets (MSDS), and check out the Toxicity Profiles for Lead and Cadmium.

Both are fairly safe to the touch - the real danger comes from contaiminating your food (or cigarettes) with unwashed hands, or breathing fumes or airborne dust. Good ventilation or a respirator, and lots of soap and water, will protect you. Clean up after yourself so any dust doesn't get spread around. If you have kids (who absorb heavy metals better, and are more suseptible to their effects), do something else instead.

Good Juju!

There is a safe alternative: Field's metal, invented by (and available from) Simon Quellen Field at scitoys.com. It is 32.5% Bismuth, 16.5% Tin, and 51.0% Indium, and melts at a mere 149°F. And costs $1000 a pound, since it's half Indium.

Another safe alternative is 62.5% Bismuth, 37.5% Tin (5 parts Bi, 3 parts Sn). Much cheaper than Field's Metal, but it melts at 202°F. Still under the boiling point of water, though.

Alloys

You will find that some alloys have multiple entries in the following table, and some entries have multiple names. There seems to be little agreement on exactly what some alloys are, or what they are called. I'm not going to try to straighten it out. "What's in a name? That which we call a rose by any other name would melt at the same temperature." Apologies to Juliet.

(For the purposes of comparison: 140°F is Rare, 160°F is Medium, and 176°F is Well Done.)

Bismuth
%
Lead
%
Tin
%
Cadmium
%
Indium
%
Temp
F
S.G. Notes
44.7 22.6 8.3 5.3 19.1 117 9.26 Cerralow 117
50.0 25.0 12.5 12.5 149 9.73 (4:2:1:1)
32.5 16.5 51.0 149 9.23 Field's Metal
50.0 26.9 12.7 10.4 149 9.29 Lipowitz's Metal, Cerrobend
50.1 26.6 13.3 10.0 158 9.76 Wood's Metal, Lipowitz's Metal, Cerrobend
50.0 26.7 13.3 10.0 158 9.29 see above
38.4 30.8 15.4 15.4 160 9.71
47.4 19.4 20.0 13.3 160 9.30 Guthrie's Metal
50.0 25.0 12.5 12.5 165 9.29 Wood's Metal, (4:2:1:1)
27.5 27.5 10.5 34.5 167 9.55
50.0 34.5 9.3 6.2 171 10.03
50.0 31.3 18.8 176 9.31 D'Arcet's Alloy
50.0 25.0 25.0 187 9.57
50.0 25.0 25.0 200 9.31 Rose's Metal, D'Arcet's Metal, (6:1:1)
50.0 31.2 18.8 201 9.82
66.7 16.7 16.7 201 9.31 (4:1:1)
50.0 31.3 18.8 202 9.31 (8:5:3)
62.5 37.5 202 9.34 (5:3)
50.0 18.8 31.3 202 9.32 Newton's Metal, (8:5:3)
55.6 33.3 11.1 203 8.83 (5:3:1)
50.0 25.0 25.0 203 8.87
47.0 35.5 17.5 208 9.92
50.0 18.8 31.3 208 9.32 (8:5:3)
50.0 30.0 20.0 212 9.31 Newton's Metal (5:3:2)
55.6 11.1 33.3 212 9.33 (5:1:3)
42.1 42.1 15.8 226 10.06
40.0 40.0 20.0 235 9.93
50.0 10.0 40.0 240 9.33
36.5 36.5 27.0 243 9.70
33.3 33.4 33.3 253 9.49
50.0 50.0 257 9.28
30.8 38.4 30.8 266 9.63
28.5 43.0 28.5 270 9.76
50.0 50.0 286 9.35
22.2 44.4 33.4 289 9.66
21.0 42.0 37.0 289 9.53
20.0 40.0 40.0 293 9.42
19.0 38.0 43.0 298 9.32
25.0 50.0 25.0 300 9.96
23.5 47.0 29.5 304 9.80
18.1 36.2 45.7 304 9.22
14.8 40.2 45.0 307 9.30
15.3 38.8 45.9 309 9.26
14.0 43.0 43.0 309 9.40
17.3 34.6 48.1 311 9.14
16.0 36.0 48.0 311 9.16
100.0 314 7.31 Pure Indium
16.6 33.2 50.2 316 9.06
10.8 43.2 46.0 318 9.32
13.7 44.8 41.5 320 z
11.2 44.4 44.4 320 9.38
10.5 42.0 47.5 320 9.27
10.2 41.0 48.8 322 9.22
10.0 40.0 50.0 324 9.17
13.3 46.6 40.1 329 9.53
11.4 45.6 43.0 329 9.44
11.7 46.8 41.5 333 9.49
40.0 60.0 334 9.34
25.0 75.0 334 9.36
33.3 66.7 336 9.36
12.8 49.0 38.2 342 9.61
12.5 50.0 37.5 352 9.64
33.3 66.7 360 9.35
37.0 63.0 361 9.34 Solder
11.1 88.9 392 9.38
25.0 75.0 392 9.36
100.0 449 8.60 Pure Cadmium
50.0 50.0 466 9.33
66.7 33.3 475 9.30
100.0 520 9.80 Pure Bismuth
100.0 610 11.37 Pure Lead
100.0 621 7.29 Pure Tin

References

Back


© 2003 W. E. Johns