Fusible alloy

A fusible alloy is a metal alloy capable of being easily fused, i.e. easily meltable, at relatively low temperatures. Fusible alloys are commonly, but not necessarily, eutectic alloys.

Sometimes the term "fusible alloy" is used to describe alloys with a melting point below 183 °C (361 °F). Fusible alloys in this sense are used for solder.

Introduction

From practical view, low melting alloys can be divided up into:

Some reasonably well known fusible alloys are Wood's metal, Field's metal, Rose metal, Galinstan, and NaK.

Applications

Melted fusible alloys can be used as coolants as they are stable under heating and can give much higher thermal conductivity than most other coolants; particularly with alloys made with a high thermal conductivity metal such as indium or sodium. Metals with low neutron cross-section are used for cooling nuclear reactors.

Such alloys are used for making the fusible plugs inserted in the furnace crowns of steam boilers, as a safeguard in the event of the water level being allowed to fall too low. When this happens the plug, being no longer covered with water, is heated to such a temperature that it melts and allows the contents of the boiler to escape into the furnace. In automatic fire sprinklers the orifices of each sprinkler is closed with a plug that is held in place by fusible metal, which melts and liberates the water when, owing to an outbreak of fire in the room, the temperature rises above a predetermined limit.[1]

Low melting alloys and metallic elements

Low melting alloys and metallic elements
Composition in weight-percent °C eutectic? Name or remark
Cs 73.71, K 22.14, Na 4.14 [2] −78.2 yes
Hg 91.5, Tl 8.5−58 yes used in low readings thermometers
Hg 100−38.8 (yes)
Cs 77.0, K 23.0−37.5
Ga 68.5, In 21.5, Sn 10 −19 no Galinstan
K 76.7, Na 23.3−12.7 yes
K 78.0, Na 22.0−11 no NaK
Ga 61, In 25, Sn 13, Zn 1 8.5 yes
Ga 62.5, In 21.5, Sn 16.010.7 yes
Ga 69.8, In 17.6, Sn 12.510.8 no
Ga 75.5, In 24.515.7yes
Cs 10028.6 (yes)
Ga 10029.8 (yes)
Rb 10039.30 (yes)
Bi 40.3, Pb 22.2, In 17.2, Sn 10.7, Cd 8.1, Tl 1.141.5yes
Bi 40.63, Pb 22.1, In 18.1, Sn 10.65, Cd 8.246.5
Bi 49, Pb 18, In 21, Sn 1258 ChipQuik desoldering alloy[3]
Bi 32.5, In 51.0, Sn 16.560.5yes Field's metal
Bi 49.5, Pb 27.3, Sn 13.1, Cd 10.170.9yesLipowitz's alloy
Bi 50.0, Pb 25.0, Sn 12.5, Cd 12.571 no Wood's metal
In 66.3, Bi 33.772yes
Bi 50, Pb 30, Sn 20, Impurities 92 no Onions' Fusible Alloy[4]
Bi 52.5, Pb 32.0, Sn 15.595yes
Bi 50.0, Pb 31.2, Sn 18.897no Newton's metal
Bi 50.0, Pb 28.0, Sn 22.094–98no Rose's metal
Bi 56.5, Pb 43.5 125yes
Bi 57, Sn 43[5] 139yes
In 100157 (yes)
Sn 62.3, Pb 37.7183yes
Sn 63.0, Pb 37.0183no Eutectic solder
Sn 91.0, Zn 9.0198yes
Sn 92.0, Zn 8.0199noTin foil
Sn 100231.9(yes)
Bi 100271.5(yes)
Tl 100304(yes)
Cd 100321.1(yes)
Pb 100327.5(yes)
Zn 100419.5 (yes)

See also

References

  1.  Chisholm, Hugh, ed. (1911). "Fusible Metal". Encyclopædia Britannica (11th ed.). Cambridge University Press.
  2. Oshe, Ed. R.W., "Handbook of Thermodynamic and Transport Properties of Alkali Metals", Oxford. UK, Blackwell Scientific Publications Ltd, 1985, p. 987
  3. Johnson Manufacturing Co, MSDS for Chip Quik Alloy w/Lead. Retrieved on February 6, 2015.
  4. Jenson, W.B. "Ask the Historian - Onion's fusible alloy", J. Chem. Ed., 2010, 87, 1050-1051.
  5. See phase diagram for the tin-bismuth binary system here: http://oregonstate.edu/instruct/engr322/Homework/AllHomework/S12/ENGR322HW4.html

Further reading

External links