Canfield Technologies: Low Melt Alloys
Plumbing
Stained Glass
Jewelry
Plating
Industrial
Low Melt Alloys
Lead Free
Brazing Alloys
Fluxes
Commercial Paste
Tinning Paints
Core Solder
Lead Free
Industrial Alloys

   These alloys are frequently called "fusible" alloys because they are easily melted at a relatively low temperature compared to most solder alloys. These alloys are made from two or more of the following elements: Bismuth, Tin, Lead, Cadmium, and Indium.
   Each of these ingredients is used to impart specific characteristics and properties to the alloy. The alloys can be selected in proportions to make binary, tertiary or quarternary alloys that melt well below their alloying elements. They are either eutectic, which means they melt at a single temperature (like a pure metal) or non-eutectic, which means they have a melting range. This range is defined as a liquidus - the temperature above which they are completely liquid, and a solidus - the temperature below which they are completely solid. The temperatures in between these are defined as the "pasty range".
   The characteristics of these alloys include: low vapor pressure, good thermal conductivity, ease of handling, high liquid fluidity, ability to be reused, and controlled thermal dimensional properties. With this last item, an alloy can be made with minimal solidification shrinkage. Unlike most metals, pure bismuth expands 3.3% of volume on changing from liquid to solid. This expansion is employed in alloys containing bismuth to offset solidification shrinkage. An alloy containing more than 55% of bismuth expand and those with less than 48% contract with solidification. Those in between alloy exhibit little change in volume.    The change in volume due to cooling is simple linear shrinkage, but some alloys show changes in the structure of the alloy, which permit castings made of these alloys to have dimensions, the same or larger than those of the mold they were cast into.
   Some of these dimensional changes can continue to occur for as long as 1000 hours after solidification. Most of these alloys stop growing after 24 hours.

Applications of Low Melt Alloys
Safety Appliances
Fire sprinklers, Boiler plugs, releasing automatic fire doors, etc.
Foundry Practice
Making patterns, proof casting, fusible cores, etc..
Radiation Shielding
Casting permanent molds for protection.
Bonding & Sealing
Soldering to glass and temperature sensitive devices. Prevents a thin wall tube from buckling on sharp bending radii.
Tube Bending
Prevents a thin wall tube from buckling on sharp bending radii.
Electroforming
To produce expendable mandrels for complicated shapes.
Figurines
Miniature pieces by centrifugal rubber mold casting.


Low Melt Alloys
Constituents -Weight Percent
Melting Points
Alloy
Bismuth
Lead
Tin
Cadmium
Indium
Silver
Solidus
Liquidus
Designation
Bi
Pb
Sn
Cd
In
Ag
°F
°C
°F
°C
117
44.7
22.6
8.3
5.3
19.1
0
117
47
117
47
136
49
18
12
0
21
0
136
58
136
58
158
50
26.7
13.3
10
0
0
158
70
158
70
158-190
42.5
37.2
11.3
9
0
0
158
70
190
88
174
57
0
17
0
26
0
174
79
174
79
203
52.5
32
15.5
0
0
0
203
95
203
95
255
55.5
44.5
0
0
0
0
255
124
255
124
281
58
0
42
0
0
0
281
138
281
138
281-338
40
0
60
0
0
0
281
138
338
170
291-325
14
43
43
0
0
0
291
144
325
163
244
0
0
48
0
52
0
244
118
244
118
296
0
0
0
0
97
3
296
147
296
147
293
0
30.5
51.2
18.3
0
0
293
145
293
145
300-302
0
15
0
0
80
5
300
149
302
150
307-323
0
18
70
0
12
0
307
153
323
162
320-345
0
30
0
0
70
0
320
160
345
174
 
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