|Research:||Phase Transformations in Ni-based Superalloys|
|Education:||B.Eng Metallurgical Engineering, McGill University|
|Publications:||Publications by Booth-Morrison in our database|
Materials Science and Engineering
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Evanston, IL 60208
The recent surge in fuel costs and the threat of global warming have amplified the urgency for increased fuel efficiency in high-performance engines. The fuel efficiency of an engine is directly related to its operating temperature, which is tied to the properties of the engine materials. Nickel-based superalloys are used for critical components of aerospace and land-based turbine engines due to their excellent strength and resistance to both corrosion and creep at temperatures up to 1373 K. The high-temperature mechanical properties of these materials are a result of strengthening of the primary γ-matrix phase by the precipitation of a secondary γ'-phase. The decomposition of the γ-matrix via the formation of nanoscale γ'-precipitates is the main subject of my thesis research.
I study the kinetic pathways of the γ-/γ'- phase transformation using high-resolution experimental techniques, namely APT and electron microscopy. Figure 1 below shows the cuboidal γ'-precipitates that form in the γ-matrix of a model Ni-Al-Cr-Ta alloy at 1073 K. In-depth analysis of datasets such as the one shown in the figure below, provide details about the temporal evolution of the γ'-precipitate properties and compositions. These results, in concert with simulations employing advanced computational methods such as first-principles calculations, and Monte-Carlo and thermodynamic simulations, elucidate the kinetic pathways that lead to phase decomposition at high-temperatures. The development of future generations of nickel-based superalloys that can withstand higher operating temperatures will rely on a detailed understanding of the γ/γ'- phase transformation. These complex multi-component alloys will serve as the building blocks for advanced turbine engines that will need less fuel, and produce fewer CO2 greenhouse gas emissions.
Figure 1- Cuboidal γ'-precipitates in Ni-10.0 Al-8.5 Cr-2.0 Ta at.% heat-treated at 1073 K for 64 h. The γ'-precipitates have aligned along the elastically soft <001>-type directions. Aluminum and tantalum atoms, shown in red and yellow, respectively, partition preferentially to the γ'-precipitates, while chromium, shown in blue, partitions to the γ'-matrix. Nickel atoms are omitted for clarity.