Zircaloy

Zircaloy is a family of zirconium-based alloys developed for nuclear applications and used primarily as fuel cladding in light-water reactors. The base metal zirconium provides a low neutron absorption cross-section and good corrosion resistance in high-temperature water, while alloying improves strength and fabricability.

Two common grades are Zircaloy-2 and Zircaloy-4. Zircaloy-2 contains tin as the principal alloying element along with small amounts of iron, chromium, and nickel; Zircaloy-4 uses similar elements but typically has little or no nickel. Both grades form a protective oxide layer in reactor water and offer a favorable balance of corrosion resistance, strength, and ease of fabrication.

They are widely used as fuel cladding in pressurized-water and boiling-water reactors, where minimizing neutron capture while maintaining integrity under irradiation and high temperatures is essential. In service, hydrogen pickup can lead to zirconium hydride formation and embrittlement; safety and performance are managed through design, inspection, and careful alloy choice.

The Zircaloy family remains a standard reference in nuclear materials, although alternative alloys and cladding concepts are under development or in limited use for specific reactor designs.