In Alclad 2024-T4, the surface layer is made of which material?

• A. commercially pure aluminum
• B. heat-treated aluminum alloy
• C. strain-hardened aluminum alloy
• D. aluminum oxide

Answer: (A)

The surface layer in Alclad is a thin skin of commercially pure aluminum added to the strong core alloy to improve corrosion resistance. In Alclad 2024-T4, the core is the high-strength aluminum-copper-magnesium alloy in T4 temper, while the outer layer is essentially pure aluminum. This pure aluminum skin shields the core from corrosion and forms a protective oxide film, without being a heat-treated or strain-hardened version of the core alloy. It is not aluminum oxide itself as the clad layer, but metallic pure aluminum. So, the surface layer is commercially pure aluminum.