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Open AccessArticle

On the Development Concept for a New 718-Type Superalloy with Improved Temperature Capability

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Technische Universität Braunschweig, Institut für Werkstoffe, Langer Kamp 8, D-38116 Braunschweig
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VDM Metals International GmbH, Plettenberger Straße 2, D-58792 Werdohl, Germany
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VDM Metals International GmbH, Kleffstraße 23, D-58762 Altena, Germany
*
Author to whom correspondence should be addressed.
Metals 2019, 9(10), 1130; https://doi.org/10.3390/met9101130
Received: 22 August 2019 / Revised: 14 October 2019 / Accepted: 15 October 2019 / Published: 22 October 2019
The superalloy 718 stands out for its excellent manufacturability and strength at ambient temperature. However, its application temperature is limited to about 650 °C due to the instability of the γ’’ precipitates. Here, we provide an in-depth account of an alloy development concept, allowing for the design of superalloys with 718-type properties, yet with a significantly improved microstructural stability. The article begins with a detailed discussion on how the microstructural and chemical composition must be altered to achieve this objective. Then, model alloys were used to explore and validate the outlined strategy. Finally, it is shown how these considerations ultimately led to a new 718-type superalloy with far more improved microstructural stability— namely, VDM Alloy 780. The introduction of a large amount of Co as a substitute for Fe (and partially Ni) is the most important element of our alloy development concept in terms of chemical composition. The most important microstructural feature is the introduction of low solvus temperature, high misfit γ´-strengthening, replacing γ´´-hardening. View Full-Text
Keywords: Ni-based superalloys; alloy development; alloy 718; Alloy 780; wrought superalloys Ni-based superalloys; alloy development; alloy 718; Alloy 780; wrought superalloys
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Rösler, J.; Hentrich, T.; Gehrmann, B. On the Development Concept for a New 718-Type Superalloy with Improved Temperature Capability. Metals 2019, 9, 1130.

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