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; 456 K). 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

Well known alloys

Alloy Melting point Eutectic? Bismuth Lead Tin Indium Cadmium Thallium Gallium Antimony
Rose's metal 98 °C (208 °F) no 50% 25% 25%
Cerrosafe 74 °C (165 °F) no 42.5% 37.7% 11.3% 8.5%
Wood's metal 70 °C (158 °F) yes 50% 26.7% 13.3% 10%
Field's metal 62 °C (144 °F) yes 32.5% 16.5% 51%
Cerrolow 136 58 °C (136 °F) yes 49% 18% 12% 21%
Cerrolow 117 47.2 °C (117 °F) yes 44.7% 22.6% 8.3% 19.1% 5.3%
Bi-Pb-Sn-Cd-In-Tl 41.5 °C (107 °F) yes 40.3% 22.2% 10.7% 17.7% 8.1% 1.1%
Galinstan −19 °C (−2 °F) yes <1.5% 9.5-10.5% 21-22% 68-69% <1.5%

Other alloys

(see also solder alloys)

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 44.7, Pb 22.6, In 19.1, Cd 5.3, Sn 8.347yesCerrolow 117. Used as a solder in low-temperature physics.[3]
Bi 49, Pb 18, In 21, Sn 1258 ChipQuik desoldering alloy.[4] Cerrolow 136. Slightly expands on cooling, later shows slight shrinkage in couple hours afterwards. Used as a solder in low-temperature physics.[3]
Bi 32.5, In 51.0, Sn 16.560.5yes Field's metal
Bi 50, Pb 26.7, Sn 13.3, Cd 1070yesCerrobend. Used in low-temperature physics as a solder.[3]
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 yes Wood's metal
In 66.3, Bi 33.772yes
Bi 42.5, Pb 37.7, Sn 11.3, Cd 8.574 no Cerrosafe
Bi 56, Sn 30, In 1479-91noChipQuik desoldering alloy, lead-free
Bi 50, Pb 30, Sn 20, Impurities 92 no Onions' Fusible Alloy[5]
Bi 52.5, Pb 32.0, Sn 15.595yes
Bi 52, Pb 32.0, Sn 1696yesBi52. Good fatigue resistance combined with low melting point. Reasonable shear strength and fatigue properties. Combination with lead-tin solder may dramatically lower melting point and lead to joint failure.[6]
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 58, Sn 42138yesBi58. Reasonable shear strength and fatigue properties. Combination with lead-tin solder may dramatically lower melting point and lead to joint failure.[6] Low-temperature eutectic solder with high strength.[7] Particularly strong, very brittle.[8] Used extensively in through-hole technology assemblies in IBM mainframe computers where low soldering temperature was required. Can be used as a coating of copper particles to facilitate their bonding under pressure/heat and creating a conductive metallurgical joint.[9] Sensitive to shear rate. Good for electronics. Used in thermoelectric applications. Good thermal fatigue performance.
Bi 57, Sn 43[10] 139yes
In 100157 (yes)In99. Used for die attachment of some chips. More suitable for soldering gold, dissolution rate of gold is 17 times slower than in tin-based solders and up to 20% of gold can be tolerated without significant embrittlement. Good performance at cryogenic temperatures.[11] Wets many surfaces incl. quartz, glass, and many ceramics. Deforms indefinitely under load. Does not become brittle even at low temperatures. Used as a solder in low-temperature physics, will bond to aluminium. Can be used for soldering to thin metal films or glass with an ultrasonic soldering iron.[3]
Sn 62.3, Pb 37.7183yes
Sn 63.0, Pb 37.0183no Eutectic solder. Sn63, ASTM63A, ASTM63B. Common in electronics; exceptional tinning and wetting properties, also good for stainless steel. One of the most common solders. Low cost and good bonding properties. Used in both SMT and through-hole electronics. Rapidly dissolves gold and silver, not recommended for those.[7] Sn60Pb40 is slightly cheaper and is often used instead for cost reasons, as the melting point difference is insignificant in practice. On slow cooling gives slightly brighter joints than Sn60Pb40.[12]
Sn 91.0, Zn 9.0198yesKappAloy9 Designed specifically for Aluminum-to-Aluminum and Aluminum-to-Copper soldering. It has good corrosion resistance and tensile strength. Lies between soft solder and silver brazing alloys, thereby avoiding damage to critical electronics and substrate deformation and segregation. Best solder for Aluminum wire to Copper busses or Copper wire to Aluminum busses or contacts.[13] UNS#: L91090
Sn 92.0, Zn 8.0199noTin foil
Sn 100231.9(yes)Sn99. Good strength, non-dulling. Use in food processing equipment, wire tinning, and alloying.[14] Susceptible to tin pest.
Bi 100271.5(yes)Used as a non-superconducting solder in low-temperature physics. Does not wet metals well, forms a mechanically weak joint.[3]
Tl 100304(yes)
Cd 100321.1(yes)
Pb 100327.5(yes)
Zn 100419.5 (yes)For soldering aluminium. Good wettability of aluminium, relatively good corrosion resistance.[15]

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. 1 2 3 4 5 Guy Kendall White; Philip J. Meeson (2002). Experimental techniques in low-temperature physics. Clarendon. pp. 207–. ISBN 978-0-19-851428-2. Retrieved 14 May 2011.
  4. Johnson Manufacturing Co, MSDS for Chip Quik Alloy w/Lead. Retrieved on February 6, 2015.
  5. Jenson, W.B. "Ask the Historian - Onion's fusible alloy", J. Chem. Ed., 2010, 87, 1050-1051.
  6. 1 2 John H. Lau (1991). Solder joint reliability: theory and applications. Springer. p. 178. ISBN 0-442-00260-2.
  7. 1 2 Ray P. Prasad (1997). Surface mount technology: principles and practice. Springer. p. 385. ISBN 0-412-12921-3.
  8. Charles A. Harper (2003). Electronic materials and processes. McGraw-Hill Professional. pp. 5–8. ISBN 0-07-140214-4.
  9. Karl J. Puttlitz, Kathleen A. Stalter (2004). Handbook of lead-free solder technology for microelectronic assemblies. CRC Press. ISBN 0-8247-4870-0.
  10. See phase diagram for the tin-bismuth binary system here: http://oregonstate.edu/instruct/engr322/Homework/AllHomework/S12/ENGR322HW4.html
  11. T.Q. Collier (May–Jun 2008). "Choosing the best bumb for the buck". Advanced Packaging. 17 (4): 24. ISSN 1065-0555.
  12. msl747.PDF. (PDF). Retrieved 2010-07-06.
  13. "KappAloy". Kapp Alloy & Wire, Inc. Retrieved 23 October 2012. |first1= missing |last1= in Authors list (help)
  14. Madara Ogot, Gul Okudan-Kremer (2004). Engineering design: a practical guide. Trafford Publishing. p. 445. ISBN 1-4120-3850-2.
  15. Howard H. Manko (8 February 2001). Solders and soldering: materials, design, production, and analysis for reliable bonding. McGraw-Hill Professional. pp. 396–. ISBN 978-0-07-134417-3. Retrieved 17 April 2011.

Further reading

External links

This article is issued from Wikipedia - version of the 9/23/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.