Hume-Rothery rules

Hume-Rothery rules, named after William Hume-Rothery, are a set of basic rules that describe the conditions under which an element could dissolve in a metal, forming a solid solution. There are two sets of rules; one refers to substitutional solid solutions, and the other refers to interstitial solid solutions.

Substitutional solid solution rules

For substitutional solid solutions, the Hume-Rothery rules are as follows:

  1. The atomic radius of the solute and solvent atoms must differ by no more than 15%:
  2. The crystal structures of solute and solvent must be similar.
  3. Complete solubility occurs when the solvent and solute have the same valency.[1] A metal with lower valency is more likely to dissolve in a metal of higher valency.[2]
  4. The solute and solvent should have similar electronegativity. If the electronegativity difference is too great, the metals tend to form intermetallic compounds instead of solid solutions.

Interstitial solid solution rules

For interstitial solid solutions, the Hume-Rothery Rules are:

  1. Solute atoms should have radius no larger than 15% of the radius of solvent atoms.[3][4][5]
  2. The solute and solvent should have similar electronegativity.[6]
  3. They should show a wide range of composition.
  4. Valency factor: two elements should have the same valence. The greater the difference in valence between solute and solvent atoms, the lower the solubility.

See also

Notes
  1. Foundations of Materials Science and Engineering, 4th ed., W. Smith and J. Hashemi, pp.139-140 (2006).
  2. VALENCY EFFECTS AND RELATIVE SOLUBILITIES IN TRANSITION METAL ALLOYS D. A. Goodman* and L. H. Bennett National Bureau of Standards, Washington DC, 20234 R. E. Watson Brookhaven National Laboratory.
  3. https://madeeasy.in/admin/ESEGroup/12.%20ME_ESE_FST_Paper-2_Conv_2109.pdf
  4. http://slideplayer.com/slide/7666224/
  5. http://slideplayer.com/slide/5866092/
  6. "Hume-Rothery Rules". Van Nostrand's Scientific Encyclopedia. John Wiley & Sons, Inc. 2002.

https://iesmaster.org/public/resources/ese-2019-prelims/ESE-2019-Prelims-GS-%26-Engineering-Aptitude-Detailed-Solution-SET-C.pdf

References

Further reading
  • Mizutani, Uichiro (2010). Hume-Rothery Rules for Structurally Complex Alloy Phases. Taylor & Francis. ISBN 978-1-4200-9058-1.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.