|Research:||Phase Transformations in Ni-based Superalloys|
|Education:||B.Eng Metallurgical Engineering, McGill University|
|Publications:||Publications by Booth-Morrison in our database|
Dr. Christopher Booth-Morrison
Materials Science and Engineering
2220 North Campus Drive
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 γ-matrix phase by the precipitation of the 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 provides details about the temporal evolution of the γ'-precipitate properties and compositions. These results, in concert with first-principles calculations and Monte-Carlo and thermodynamic simulations, elucidate the kinetic pathways that lead to high-temperature phase decomposition. 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.% aged 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.