An interstitial alloy is a metal alloy formed when small non-metal atoms occupy the interstitial (gap) between the larger metal atoms in a metal's crystal arrangement. The smaller atoms do not replace the metal atoms but fit in the gaps, thus forming a solid solution of the metallic alloy.
Key Features:
- Small Atoms in Gaps: The elements used in interstitial alloys tend to be smaller atoms. For example, carbon, nitrogen, or hydrogen are small enough that they can take up space between metal atoms (like iron crystals).
- Increased Strength, Hardness, or Impact Resistance: By adding the interstitial atoms, the original crystal was distorted and led to difficulty in dislocation mobility, which contributes to increased mechanical strength.
- Examples:
- Steel: The few carbon atoms occupying the interstitial spaces of the iron crystals created an interstitial alloy that increases hardness greatly.
- Titanium-nitrogen alloys: Alloys are commonly used in aerospace and medical applications to take advantage of their high strength and corrosion resistance.
However, interstitial alloys are commonly found in a host of engineering and industrial applications for their high strength, high wear resistance, and high hardness. For example, adding small amounts of carbon significantly enhances the mechanical properties of carbon steel while causing minimal changes to its structure. Interstitial alloys are used in construction, transportation, machinery, tools, and beyond because of their unique mechanical properties as they pertain to the material for a specific application. Overall, the physical behavior of the interstitial atomic atoms can be manipulated in a metallic lattice to achieve exactly the properties that you want, such as strength, ductility, etc.