Pack Aluminization Synthesis of Superalloy 3D Woven and 3D Braided Structures

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2015-01, Vol.46 (1), p.426-438
• Main Authors: Erdeniz, Dinc, Levinson, Amanda J., Sharp, Keith W., Rowenhorst, David J., Fonda, Richard W., Dunand, David C.
• Format: Article
• Language: English
• Subjects: Aluminides; Characterization and Evaluation of Materials; Chemical precipitation; Chemistry and Materials Science; Density; Intermetallic compounds; Intermetallics; Materials Science; Metallic Materials; Metallurgy; Microstructure; Nanotechnology; Nickel base alloys; Nickel compounds; Precipitation; Structural Materials; Superalloys; Surfaces and Interfaces; Thin Films; Three dimensional; Wire
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-014-2602-9

Micro-architectured, precipitation-strengthened structures were created in a new process combining weaving, gas-phase alloying, diffusion, and precipitation. First, high-ductility Ni-20 wt pct Cr wires with 202  μ m diameter were braided, or non-crimp orthogonal woven, into three-dimensional structures. Second, these structures were vapor-phase alloyed with Al at 1273 K (1000 °C) by pack cementation, creating uniform NiAl coatings on the wires when using a retort. Also, solid-state bonding was achieved at wire intersections, where two wires were sufficiently close to each other, as determined via optical and X-ray tomographic microscopy. Third, the NiAl-coated wires were fully homogenized and aged to form γ ′ precipitates distributed in a γ matrix phase, the same microstructure providing strength in nickel-based superalloys. The resulting structures—consisting of wires (i) woven in a controlled three-dimensional architecture, (ii) bonded at contact points and (iii) strengthened by γ ′ precipitates—are expected to show high strength at ambient and elevated temperatures, low density, and high permeability which is useful for active cooling.