New Webinar: Atom Probe Tomography - Directing the Next Generation of Superalloys
Tuesday, July 22nd, 10AM CST
Register here
Single-crystal Ni-base superalloys are multi-element (> ~ 10 elements) alloys that are critical for the parts of high-temperature turbine engines. Over the years, multiple generations of superalloys were developed, where the latest compositions involve dense and Rare-Earth elements such as Re and Ru (up to 6 wt.%), making them heavier and costlier. Hence, it has a direct negative impact on engine efficiency and higher CO2 emissions.
Here, we use Atom Probe Tomography (APT) in correlation with electron microscopy to reveal the effect of solutes on the plastic deformation under stress at high temperatures. The results reveal the selective segregation of solutes at the atomic scale to the different types of defect structures produced in a 2nd generation CMSX-4 Ni-base single-crystal alloy. The results indicate compositional variation of solutes along the twin boundaries, and based on segregation behavior, we introduce the requirement of an additional reordering step in Kolbe’s mechanism of micro-twinning that can be one of the rate-limiting steps for the creep deformation.
Based on these observations, other than Re, the possible creep rate-limiting solutes were identified, and new compositions were designed with lower Re (by 1.5 wt.%) content. These show exceptional creep resistance compared to the base CMSX-4 composition in polycrystalline form. The study opens avenues for new superalloys for more energy-efficient and cost-effective turbine engines with lower CO2 emissions.
Dr. Surendra Kumar Makineni of Indian Institute of Science will present. Q&A will follow the presentation.
