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

JOURNAL OF ALLOYS AND COMPOUNDS

卷:814

Article

Ghica, C.¹  Solis, C.²  Munke, J.²  Stark, A.³  Gehrmann, B.⁴  Bergner, M.⁵  Roesler, J.⁵  Gilles, R.² 

[1] Natl Inst Mat Phys, Magurele 077125, Romania

[2] Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, D-85748 Garching, Germany

[3] Helmholtz Zentrum Geesthacht, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany

[4] VDM Met Int GmbH, Kleffstr 23, D-58762 Altena, Germany

[5] Tech Univ Carolo Wilhelmina Braunschweig, Inst Werkstoffe, D-38106 Braunschweig, Germany

关键词: Ni-base superalloys;    HRTEM;    EELS;    STEM;    HAADF;   

DOI  :  10.1016/j.jallcom.2019.152157

来源: Elsevier

【 摘 要 】

VDM 780 Premium is a recently developed Ni-based superalloy designed for working at high service temperatures (above 650 degrees C) while keeping the good workability of alloy 718. VDM 780 Premium is based on the austenitic matrix (gamma phase) strengthened by intermetallic Ni3Al-like precipitates (gamma' phase, fcc L1(2) structure). Other co-precipitates may be formed in function of the applied heat treatment, such as Ni3Nb-based (delta phase, orthorhombic DOa structure) or Ni3Ti-based (eta phase, hexagonal DO24 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 delta/eta structure of the precipitates. (C) 2019 Published by Elsevier B.V.

【 授权许可】

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