Christopher Booth-Morrison

Research:	Phase Transformations in Ni-based Superalloys
Education:	B.Eng Metallurgical Engineering, McGill University
Publications:	Publications by Booth-Morrison in our database
Contact
Dr. Christopher Booth-Morrison Materials Science and Engineering 2220 North Campus Drive Evanston, IL 60208 Phone: 847.491.5883 Email: c-booth@northwestern.edu Fax: 847.467.2269

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.