D.J. Crudden

Characterization of Phase Chemistry and Partitioning in a Family of High-Strength Nickel-Based Superalloys

A family of novel polycrystalline Ni-based superalloys with varying Ti:Nb ratios has been created using computational alloy design techniques, and subsequently characterized using atom probe tomography and electron microscopy. Phase chemistry, elemental partitioning, and γ′ character have been analyzed and compared with thermodynamic predictions created using Thermo-Calc. Phase compositions and γ′ volume fraction were found to compare favorably with the thermodynamically predicted values, while predicted partitioning behavior for Ti, Nb, Cr, and Co tended to overestimate γ′ preference over the γ matrix, often with opposing trends vs Nb concentration.

Atom Probe Characterization of Oxide Layers Formed on Polycrystalline Nickel Based Superalloys

Nickel based superalloys are a class of high-temperature materials used extensively throughout the high pressure sections of jet turbine engines. Two characteristics that make them particularly suited to this application are the ability to maintain strength at high temperatures, combined with the formation of a protective oxide scale which prevents further oxidation damage. These characteristics are prime motivations during the alloy design process.