Episode 70: Nickel Superalloys at General Electric
Aug 17, 2023
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Discover the evolution of nickel superalloys in aerospace, their strength mechanisms, and manufacturing processes for jet engine parts. Explore challenges in acquiring metallic materials and the role of materials innovation at General Electric.
Nickel superalloys are crucial for high-temperature applications in aerospace engineering, enhancing engine efficiency.
Maintaining stability of properties in superalloys at high temperatures involves interaction with oxide scales and use of coatings.
Microstructure, like gamma prime phase, plays a key role in providing exceptional strength at high temperatures in superalloys.
Deep dives
Importance of Super Alloys in Aerospace Engineering
Super alloys have been vital to aerospace engineering, especially for high-temperature applications in jet engines. General Electric's history with super alloys dates back to the early 20th century, with a focus on high-temperature metals to enhance engine efficiency. The Brayton cycle's thermal efficiency emphasizes the need for high-temperature metals like super alloys, enabling optimal energy extraction from fuel.
Challenges of Employing Materials at High Temperatures
Employing materials at higher temperatures poses challenges such as maintaining mechanical and environmental properties. Super alloys undergo extensive characterization to ensure stability over time at high temperatures. The stability of properties over time, interaction with protective oxide scales, and the use of coatings play crucial roles in maintaining material integrity under harsh conditions.
Unique Properties of Super Alloys and Microstructure
Super alloys exhibit unique properties due to their microstructure, particularly the gamma prime phase in nickel-based super alloys. The well-structured gamma prime phase embedded in a matrix provides exceptional strength at high temperatures. The microstructure, like dislocation blocks formed by cross-slipping, creates strengthening obstacles that enhance materials' resistance to deformation. Understanding the microstructure's role in strengthening and temperature dependency highlights the intricate nature of super alloys.
Innovations in Alloy Systems and Additive Manufacturing
Recent developments in cobalt base alloys have revealed L12 precipitate strengthening, sparking interest in different alloy systems. The exploration of electron beam and laser powder bed melting machines by GE led to the investigation of superalloys and potential applications in additive manufacturing processes. Researchers are now delving into refractory materials, transitioning from face center cubic to body center cubic alloy systems, seeking comparable strengthening mechanisms while balancing density and durability challenges.
Physics-Driven Models and Alloy Design Approaches
The development of high-strength, high-temperature superalloys requires predicting phase stability, precipitate size, and microstructural evolution. GE employs physics-driven models to optimize alloy compositions and processing parameters, considering factors like interfacial energy and diffusivity. Utilizing machine learning, high-throughput experiments, and advanced characterization techniques aid in predicting phase diagrams, segregation, and precipitation behavior. The focus is on balancing properties and optimizing microstructures through computational materials engineering and leveraging decades of industry expertise.
Modern engineers work in environments that most metals simply can't withstand. What do you do when you need a metal to go to incredibly high temperatures? You make an alloy. We take a dive into the history of these nickel "superalloys" to understand what makes them so super and how they are being leveraged to push innovation forward.
Interested in learning more? Check out these awesome resources from TMS:
This episode is sponsored by GE, a leading company in a multitude of fields. Check out their research homepage here. Take a look at jobs here
This episode is sponsored by Materials Today, an Elsevier community dedicated to the creation and sharing of materials science knowledge and experience through their peer-reviewed journals, academic conferences, educational webinars, and more.
Thanks to Kolobyte and Alphabot for letting us use their music in the show!
If you have questions or feedback please send us emails at materialism.podcast@gmail.com or connect with us on social media: Instagram, Twitter.
Materialism Team: Taylor Sparks (co-creator,co-host), Andrew Falkowski (co-creator,co-host,editing assistance), Jared Duffy (production, marketing, and editing).
Keywords: Materials Science Nickel Superalloy High Temperature Metals High Hardness Work Hardening General Electric
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