Effect of Heat Treatment on Microstructure and Mechanical Properties of VDM Alloy 780 Premium

Bergner, M.; Rösler, Joachim; Gehrmann, Bodo; Klöwer, J.

doi:10.1007/978-3-319-89480-5_31

Cited by 9 publications

(13 citation statements)

References 10 publications

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“…Further information regarding the g 0 precipitation in the VDM 780 Premium alloy can be found in Ref. [7]. The Rietveld refinements of the synchrotron diffraction patterns measured at the P07-HEMS [22] instrument at PETRA III (DESY) for samples VDM 780-a and VDM 780-b are presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The heat treatments were selected for setting up different microstructures. Thus, sample VDM 780-a was produced, containing mainly the g matrix and the high-temperature phase, while sample VDM 780-b shows in addition a large amount of g 0 hardening precipitates [6,7]. In sample VDM 780-a the heat treatment at 1000 C ensures the complete dissolution of g 0 phase, while the aim of the step at 975 C for 16 h is to obtain a significant amount of high-temperature phase along the grain boundaries.…”

Section: Methodsmentioning

confidence: 99%

“…As in Nickel Alloy 718, the d phase may be used for forming fine grain size during the forging and the recrystallization, hindering the grain growth. However, although the fine-grained structure provides high strength at ambient temperature, grain boundaries become weak areas at elevated temperatures [7]. Furthermore, it has been shown that in some cases of Alloy 718Plus the presence of nanoscale h phase precipitates creates a low-energy structure that inhibits the accumulation of stacking faults into twins, leading to a significant improvement of the creep properties [15].…”

Section: Introductionmentioning

confidence: 99%

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HRTEM analysis of the high-temperature phases of the newly developed high-temperature Ni-base superalloy VDM 780 Premium

Ghica

Solís

Munke

et al. 2020

Journal of Alloys and Compounds

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VDM 780 Premium is a recently developed Ni-based superalloy designed for working at high service temperatures (above 650 C) while keeping the good workability of alloy 718. VDM 780 Premium is based on the austenitic matrix (g phase) strengthened by intermetallic Ni 3 Al-like precipitates (g' phase, fcc L1 2 structure). Other co-precipitates may be formed in function of the applied heat treatment, such as Ni 3 Nb-based (d phase, orthorhombic DO a structure) or Ni 3 Ti-based (h phase, hexagonal DO 24 structure) precipitates. The amount as well as the size and morphology of the different precipitates depend on the heat treatments performed on the alloy, playing an important role in improving the creep properties or the behavior during forging and recrystallization. This work contains a complex study using various techniques of analytical electron microscopy and synchrotron diffraction intended to clarify the structure of the high-temperature phase formed in the newly developed VDM 780 Premium alloy. The atomic structure of the high-temperature plate-like precipitates formed in VDM 780 Premium after two different thermal treatments has been investigated in relation with the surrounding matrix lattice, proving the stacked d/h structure of the precipitates.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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HRTEM analysis of the high-temperature phases of the newly developed high-temperature Ni-base superalloy VDM 780 Premium

Ghica

Solís

Munke

et al. 2020

Journal of Alloys and Compounds

Self Cite

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“…As alloy V17 exhibited excellent microstructural stability, a high flow strength, reasonably slow precipitation kinetics of the γ -phase, and the ability for fine grain forging due to the presence of the δ-phase, this composition essentially became VDM Alloy 780, being now introduced into the market by VDM Metals GmbH. According to reference [36], the chemical composition of VDM Alloy 780 is Ni-25Co-18Cr-3Mo-2.0Al-0.2Ti-5.4Nb. Further information on the mechanical properties and microstructural evolution of VDM Alloy 780 can be found in References [36,40].…”

Section: The Effect Of the Al/ti Ratiomentioning

confidence: 99%

“…According to reference [36], the chemical composition of VDM Alloy 780 is Ni-25Co-18Cr-3Mo-2.0Al-0.2Ti-5.4Nb. Further information on the mechanical properties and microstructural evolution of VDM Alloy 780 can be found in References [36,40]. This is not the subject of discussion in this article, which had the objective to outline the history of the alloy development with the underlying condsiderations.…”

Section: The Effect Of the Al/ti Ratiomentioning

confidence: 99%

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

Rösler

Hentrich²,

Gehrmann³

2019

Metals

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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.

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Microstructural Stability and Properties of New Nickel‐Base Superalloys with Varying Aluminium: Niobium Ratio

et al. 2023

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New nickel‐base superalloys with higher temperature capability are required for future, more efficient gas turbine engines. In designing such alloys, careful consideration is required of the elemental concentrations to ensure a suitable balance of properties is obtained. Herein, the phase equilibria and microstructural stability of new nickel‐base superalloys with varying Al:Nb ratio are assessed via long‐term thermal exposures at 700 °C. The alloys are analyzed using scanning and transmission electron microscopy, X‐ray diffraction, differential scanning calorimetry, and Vickers hardness testing, with the results rationalized through mechanical property predictions based on strong‐ and weak‐pair dislocation coupling mechanisms. The alloys are shown to have greater thermal stability than Inconel 718 and exhibit a pronounced hardening effect after thermal exposure. Herein, their ability for controlled age hardening and potential ease of processing is highlighted in the results.

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Effect of Heat Treatment on Microstructure and Mechanical Properties of VDM Alloy 780 Premium

Cited by 9 publications

References 10 publications

HRTEM analysis of the high-temperature phases of the newly developed high-temperature Ni-base superalloy VDM 780 Premium

HRTEM analysis of the high-temperature phases of the newly developed high-temperature Ni-base superalloy VDM 780 Premium

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

Microstructural Stability and Properties of New Nickel‐Base Superalloys with Varying Aluminium: Niobium Ratio

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