Post-fabrication vapor phase strengthening of nickel-based sheet alloys for thermostructural panels

High-temperature metallic systems for use in thermostructural sandwich panels are important for many hypersonic flight systems. The complex three-dimensional geometry of these structures poses fabrication challenges for high-strength, high-temperature alloys. A new processing technique involving post-fabrication strengthening via pack aluminization has been investigated. Aluminization produces a β-NiAl surface layer, which is decomposed in subsequent annealing treatments, distributing Al through the sheet thickness. Microstructural development through the stages of processing is discussed along with mechanical properties of the post-fabrication, precipitation-strengthened sheet. Additionally, the benefit of this process to the oxidation behavior of these structures is discussed.