Hume-Rothery rule [ ′hyüm ′rȯth·ə·rē ‚rül] (solid-state physics) The rule that the ratio of the number of valence electrons to the number of atoms in a given phase of an electron compound depends only on the phase, and not on the elements making up the compounds.
What is Hume Rothery rule in chemistry?
Hume-Rothery rule. The rule that the ratio of the number of valence electrons to the number of atoms in a given phase of an electron compound depends only on the phase, and not on the elements making up the compounds.
What did Herbert Hume Rothery study?
Hume-Rothery (1899-1968) was a metallurgist who studied the alloying of metals. His research was conducted at Oxford University where in 1958, he was appointed to the first chair in metallurgy. His research led to some simple and useful rules on the extent to which an element might dissolve in a metal [1-4].
What are the Hume-Rothery rules for alloys?
Alloys are usually improved when another element is dissolved in a substitutional site. The Hume-Rothery rules essentially predict if a combination of metals will result in a substitutional solution instead of an interstitial solution or an intermetallic. 1. Similar Ionic Radii
What is Hume-Rothery?
Nichole is a research scientist with a PhD in Materials Science & Engineering. Christianlly has taught college physics and facilitated laboratory courses. He has a master's degree in Physics and is pursuing his doctorate study. The Hume-Rothery rules were developed to explain how two solids can or cannot create a solid solution.
What are the 4 Hume-Rothery rules?
the Hume-Rothery rules are:The atomic radii of the solute and solvent atoms must differ by no more than 15%:The crystal structures of solute and solvent must match.Maximum solubility occurs when the solvent and solute have the same valency. ... The solute and solvent should have similar electronegativity.
What is relative valence factor?
(d) Relative valence factor: ❖ A metal of higher valency can dissolve a small amount of lower valency metal. The. solute and solvent atoms should typically have the same valence in order to. achieve maximum solubility.
What does the Hume-Rothery rule tell us?
For interstitial solid solutions, the Hume-Rothery Rules are: Solute atoms should have a smaller radius than 59% of the radius of solvent atoms. The solute and solvent should have similar electronegativity. Valency factor: two elements should have the same valence.
What is Hume-Rothery rule and explain with suitable examples?
Just as two liquids can mix to form a liquid solution, two solids can mix to form a solid solution. For example, copper and nickel mix to form a solid solution. This means that the copper and nickel atoms completely mix with each other no matter how much copper or nickel there is.
What Is A Substitutional Solid Solution?
Similar Ionic Radii
- Hume-Rothery’s first rule says that the ionic radii need to be within 15% of each other. That is, There are two reasons why ionic radii is important. First, if the solute atom is small enough to fit into the interstitial site of the solvent atoms, it will almost always be interstitial instead of substitutional. Simple geometry. But even if the solu...
Same Crystal Structures
- For two elements to have appreciable solubility, they need to have the same crystal structure. You can see how it might induce strain if a substitutional atom wants to pack differently than the surrounding atoms. The “natural” crystal structure of each element is due to quantum mechanics. And of course, there are exceptions to this rule. For example, stainless steel is mostly iron, with …
Similar Electronegativity
- The next-most important similarity for solubility is electronegativity. Electronegativity is a property that says how badly an element wants to steal an electron. Atoms with high electronegativities will take electrons from nearby atoms with lower electronegativities. If two elements have a large electronegativity difference, they will be attracted to each other because one atom will pull on an…
Similar Valency
- The final Hume-Rothery rule–with the most exceptions–is that the atoms should have a similar valency. Valency is the number of electrons in the atom’s outer shell. In other words, mutually soluble elements will typically be in the same column of the periodic table. They could also be one or two columns off, but maximum solubility will happen if they have the same valency. Personall…
Are Hume-Rothery Rules Still Important?
- As a student who may need to intuitively guess how materials will behave on a test, Hume-Rothery rules are very useful. In modern research however, we have more advanced tools. I already showed a glimpse of Darken-Gurry maps, which is one improvement. We also have computational tools such as CALPHAD which can predict much more complex phases. Hume-Rothery rules onl…
References and Further Reading
- Click here to read Hume-Rothery’s original paper. You can also check out Hume-Rothery’s follow-up paper. A quick run through of real-life applications of Hume-Rothery rulesis presented by Dr. Bhadeshia at Cambridge. Shenyang National Laboratory for Materials Science hosts an advanced presentationon Hume-Rothery rules and metals. Hereyou’ll find a research paper combining Hu…