Correlation Between Local Chemical Composition and Formation of Different Types of Ordered Phases in the Polycrystalline Nickel-Base Superalloy A718Plus

Hausmann D, Förner A, Pröbstle M, Huenert D, Felfer P, Göken M, Neumeier S (2021)

Publication Type: Journal article

Publication year: 2021

Journal

DOI: 10.1002/adem.202100558

Abstract

Allvac 718Plus is a derivative of alloy 718 for applications at higher temperatures in rotating and static components of gas turbines. According to literature, various phases as γ, γ′, η, δ, and γ″ can form with so far contradicting results. Herein, the precipitation behavior in different alloy conditions is investigated using transmission electron microscopy and atom probe tomography. The aim is to clarify how local variations in chemical composition alter the sequence of precipitation and type of precipitates that form. Material conditions with a minor volume fraction of η/δ phase and a high fraction of primary γ′ precipitates form γ″ phase due to excess of available Nb. Spherical γ′ precipitates with disc-shaped γ″ precipitates at γ′ interfaces are observed. During discontinuous coarsening of η/δ plates mainly Nb is consumed which leads to an enrichment of γ′ forming elements and hence the heterogeneous nucleation of γ′ at the η/γ interface. The coexistence of thin η plates embedded in δ phase in grain boundary pinning precipitates could additionally be confirmed. These results show under which conditions certain primary phases form and how the resulting consumption and redistribution of phase promoting elements trigger the formation of other secondary phases.

Authors with CRIS profile

Additional Organisation(s)

Involved external institutions

Rolls-Royce Deutschland Ltd & Co KG Germany (DE)

How to cite

APA:

Hausmann, D., Förner, A., Pröbstle, M., Huenert, D., Felfer, P., Göken, M., & Neumeier, S. (2021). Correlation Between Local Chemical Composition and Formation of Different Types of Ordered Phases in the Polycrystalline Nickel-Base Superalloy A718Plus. Advanced Engineering Materials. https://doi.org/10.1002/adem.202100558

MLA:

Hausmann, Daniel, et al. "Correlation Between Local Chemical Composition and Formation of Different Types of Ordered Phases in the Polycrystalline Nickel-Base Superalloy A718Plus." Advanced Engineering Materials (2021).

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