Journal Article

PUBDB-2026-00591

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Post hot-deformation precipitation behavior of γ′ phase in VDM® alloy 780 under varying cooling rates and aging temperatures: An in situ high energy XRD study

Fritton, M. (Corresponding author)Extern* ; Nagel, O.Extern* ; Kümmel, F.Extern* ; Stark, A.Extern*Hereon* ; Hafez-Haghighat, M. ; Gehrmann, B. ; Neumeier, S.Extern* ; Gilles, R.Extern*

2025
Elsevier Lausanne

This record in other databases:  

Please use a persistent id in citations: doi:10.1016/j.jallcom.2025.182111  doi:10.3204/PUBDB-2026-00591

Abstract: The performance of polycrystalline Ni-based superalloys is largely determined by the fraction and size of theintermetallic hardening phases, such as the γ′ phase. Understanding the evolution of the γ′ precipitate size andvolume fraction during the complex thermomechanical process chain is essential for optimizing the mechanicalproperties of polycrystalline Ni-based superalloys. In this study, the high temporal resolution of in situ synchrotronX-ray diffraction at elevated temperatures was used to monitor γ′ evolution in VDM® Alloy 780 duringcooling and subsequent aging heat treatments in real time. To simulate the industrial forging process, the alloywas initially subjected to compressive deformation at 1000 ◦C. In the first part of the study, immediately after hotforming, three different cooling rates (10 ◦C/min, 100 ◦C/min, and 1000 ◦C/min) were applied to analyse the insitu evolution of γ′ precipitation. The resulting γ′ phase fraction was highest at the slowest cooling rate, yet eventhe fastest cooling rate did not completely suppress precipitation. In the second part of the study, the agehardeningresponse of the alloy was examined at holding temperatures of 720 ◦C and 800 ◦C for five hourseach. The evolution of the γ′ volume fraction, precipitate size, and lattice parameter was monitored in situ byXRD. After aging, γ′ volume fractions of 15 % and 19 % were obtained, with average precipitate sizes of 9 nm and18 nm, respectively. The prior deformation enhanced γ′ formation at 720 ◦C compared to literature data.Complementary Transmission Electron Microscopy (TEM) measurements confirmed precipitate sizes consistentwith the diffraction data.

---

Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. Helmholtz-Zentrum Hereon (Hereon)

Research Program(s):

1. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)

Experiment(s):

1. PETRA Beamline P07 (PETRA III)

---

Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

---