Well, there are hundreds of materials used throughout the ISS, so I can't talk about them all. The most common material is 2219-T6 aluminum alloy. Most of the ISS structure is aluminum. In fact, the Node modules were each made from single blocks of aluminum.

When you look at the outside of the ISS, some of the surface is covered with debris protection blankets made from Nextel and/or Kevlar. Some of it is covered with aluminized polyimide MLI (multi-layer insulation). In some places you'll see beta cloth. Beta cloth is a fabric made from silica and coated with Teflon.

Exposed exterior metal is usually anodized or otherwise coated for thermal efficiency and to prevent atomic oxygen reactions. Some of the metal panels are aluminum Whipple shields used to absorb the energy of a micrometeoroid.

Inside the ISS you'll find a lot of aluminum. Interior surfaces are usually coated or painted. Where possible, we avoid flammable materials, so, for example, wiring might have silicon insulation instead of PVC insulation. Hoses are often Teflon.

The payload racks have an aluminum frame but an outer shell made of graphite-fiber reinforced epoxy.

Other materials are used as needed. For example, the four control moment gyroscopes each contain a 100 kg (220 lb) solid steel wheel.