Advanced Topic 325 of 1102 States of Matter & Solutions
Solid Solutions
Homogeneous solid mixtures such as alloys.
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In-depth explanation of Solid Solutions
A solid solution is a homogeneous solid mixture in which atoms of one component are dispersed uniformly within the crystal lattice of another. In substitutional solid solutions, solute atoms replace host atoms on lattice sites, which requires similar atomic sizes, as summarized by the Hume-Rothery rules. In interstitial solid solutions, small solute atoms such as carbon or nitrogen fit into the spaces between host atoms. Solid solutions form a single phase with uniform composition, and their properties vary with composition. Alloys are the most important engineering examples of solid solutions.
Going deeper: Solid Solutions
Key ideas: Hume-Rothery rules for substitution: atomic radii within about 15 percent, same crystal structure, similar electronegativity, and similar valence. Interstitial solutes must be small, usually radius ratio below about 0.59, as in C, N, H and B. Vegard's law says that the lattice parameter varies linearly with composition. Cu-Ni forms a complete series of solid solutions.
Common mistakes and connections: Students think a solid solution is a compound or a mechanical mixture; it is a single phase with random distribution. Another error is saying all alloys are solid solutions; some, like solder with separate phases, are not. Ordering can occur at low temperature, forming superlattices. Links to alloys, defects, phase diagrams and steel.
Visualization of Solid Solutions
A solid solution disperses one component in the lattice of another, either substitutional or interstitial, as with carbon atoms in iron. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Steel is an interstitial solid solution in which carbon atoms fit into gaps between iron atoms.
Frequently asked questions about Solid Solutions
What is Solid Solutions?
Homogeneous solid mixtures such as alloys.
Is Solid Solutions a beginner, intermediate or advanced topic?
Solid Solutions is a advanced topic in States of Matter & Solutions. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Solid Solutions?
Study these earlier topics in States of Matter & Solutions first: Langmuir Isotherm, Coagulation, Hardy-Schulze Rule.
What comes after Solid Solutions?
The next topics in States of Matter & Solutions are Alloys and Dissolution Enthalpy.
Can I practise Solid Solutions with quizzes?
Yes. The interactive lesson includes a self-check question on Solid Solutions, and the States of Matter & Solutions quiz draws on every topic in this area.
Where Solid Solutions fits in States of Matter & Solutions
Solid Solutions is topic 106 of 109 in States of Matter & Solutions.