High-Temperature Performance of Actively Cooled Vapor Phase Strengthened Nickel-Based Thermostructural Panels

Abstract

Actively cooled thermostructural panels for use in emerging hypersonic flight systems require advanced materials able to support substantial loads at elevated temperatures. Identifying formable structural materials with strength, toughness, and oxidation resistance is a major challenge in this advancing technology. Geometrical optimization of thermostructural panels for scramjet applications minimizing mass with appropriate mechanical strength and cooling capacity combinations often requires submillimeter wall and face-sheet thicknesses. A new processing method was developed, resulting in rectangular-channeled panels made of nickel-based precipitation-strengthened alloy in a previously unobtainable thin-walled geometry suitable for active cooling. The processing method begins with panel fabrication from submillimeter-thin sheets of a Ni-based solid-solution alloy. The strength of the panel is subsequently increased by vapor phase aluminization combined with an annealing treatment. The vapor phase strengthening process increases the yield strength of the panel by a factor of approximately three. Panels were fabricated with geometry representative of optimal designs and tested at high temperature with active cooling in both as-fabricated and strengthened states. The strengthened, actively cooled panel withstood a temperature 478 C higher than the as-fabricated panel before failure under high heat flux conditions, indicating that the vapor phase strengthening process provides substantial new performance capabilities.

Emerging materials for microelectromechanical systems at elevated temperatures

“…In these cases, an additional homogenization step results in a uniform Ni-Al alloy 109,110 or a desired twophase c/c9 microstructure with the corresponding high temperature mechanical stability. 111,112 Conversion of LIGA Ni MEMS components to a Ni-rich two-phase (c-c9) superalloy microstructure via pack aluminization has recently been explored by Burns et al 113 The aluminized components showed significantly improved microstructural stability. Furthermore, the trimodal distribution of c9-precipitates resulted in marked improvements in both room and elevated temperature strength.…”