MC decomposition and boride formation in a next generation polycrystalline Ni based superalloy during isothermal exposure at 900 °C

H.S. Kitaguchi; L. Small; I.P. Jones; Y.L. Chiu; M.C. Hardy; P. Bowen

doi:10.1016/j.matchar.2024.113721

MC decomposition and boride formation in a next generation polycrystalline Ni based superalloy during isothermal exposure at 900 °C

H.S. Kitaguchi^*, L. Small, I.P. Jones, Y.L. Chiu, M.C. Hardy, P. Bowen

^*Corresponding author for this work

Metallurgy and Materials

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Abstract

Detailed microstructural characterisation of phases present in a next generation polycrystalline Ni based superalloy after thermal exposure at 900 °C was carried out, focusing on carbides and borides. Metastable M5B3 precipitated after 32 h had a stoichiometry of (Cr0.7Mo0.2W0.1)5B3 with substitutions with Ni, Co, Nb and Ta. Fine M23C6 (a = 10.62 Å) was overgrown by metastable M5B3, as shown by rigorous TEM-SAD pattern investigation. The borides were eventually dominated by Mo rich M3B2, at the apparent expense of MC. Decomposition of MC was confirmed; it transformed sequentially to γ and then γ΄. The primary driving force for the MC decomposition was attributed to γ΄ precipitation, increasing its fraction to the thermodynamic equilibrium at 900 °C.

Original language	English
Article number	113721
Journal	Materials Characterization
Volume	209
Early online date	1 Feb 2024
DOIs	https://doi.org/10.1016/j.matchar.2024.113721
Publication status	Published - 1 Mar 2024

Bibliographical note

Acknowledgement
The joint support of UK Engineering and Physical Science Research Council (EPSRC) and Rolls-Royce plc is greatly acknowledged. HSK and LS would like to thank Centre for Electron Microscopy (CEM) and Metallurgy&Materials Characterisation Facility at University of Birmingham for the support throughout the experimental investigations.

Keywords

Superalloys
Iso-thermal treatment
Carbides: MC M23C6
Borides: M5B3 M3B2
TEM
EDS
Thermo-Calc software

Access to Document

10.1016/j.matchar.2024.113721Licence: Creative Commons: Attribution (CC BY)

KitaguchiHS2024MCdecompositionFinal published version, 11.6 MBLicence: Creative Commons: Attribution (CC BY)

https://linkinghub.elsevier.com/retrieve/pii/S1044580324001025

Cite this

@article{91b299a8f5fd45fba3f2b1d26e6e0185,

title = "MC decomposition and boride formation in a next generation polycrystalline Ni based superalloy during isothermal exposure at 900 °C",

abstract = "Detailed microstructural characterisation of phases present in a next generation polycrystalline Ni based superalloy after thermal exposure at 900 °C was carried out, focusing on carbides and borides. Metastable M5B3 precipitated after 32 h had a stoichiometry of (Cr0.7Mo0.2W0.1)5B3 with substitutions with Ni, Co, Nb and Ta. Fine M23C6 (a = 10.62 {\AA}) was overgrown by metastable M5B3, as shown by rigorous TEM-SAD pattern investigation. The borides were eventually dominated by Mo rich M3B2, at the apparent expense of MC. Decomposition of MC was confirmed; it transformed sequentially to γ and then γ΄. The primary driving force for the MC decomposition was attributed to γ΄ precipitation, increasing its fraction to the thermodynamic equilibrium at 900 °C.",

keywords = "Superalloys, Iso-thermal treatment, Carbides: MC M23C6, Borides: M5B3 M3B2, TEM, EDS, Thermo-Calc software",

author = "H.S. Kitaguchi and L. Small and I.P. Jones and Y.L. Chiu and M.C. Hardy and P. Bowen",

note = "Acknowledgement The joint support of UK Engineering and Physical Science Research Council (EPSRC) and Rolls-Royce plc is greatly acknowledged. HSK and LS would like to thank Centre for Electron Microscopy (CEM) and Metallurgy&Materials Characterisation Facility at University of Birmingham for the support throughout the experimental investigations.",

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doi = "10.1016/j.matchar.2024.113721",

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T1 - MC decomposition and boride formation in a next generation polycrystalline Ni based superalloy during isothermal exposure at 900 °C

AU - Kitaguchi, H.S.

AU - Small, L.

AU - Jones, I.P.

AU - Chiu, Y.L.

AU - Hardy, M.C.

AU - Bowen, P.

N1 - Acknowledgement The joint support of UK Engineering and Physical Science Research Council (EPSRC) and Rolls-Royce plc is greatly acknowledged. HSK and LS would like to thank Centre for Electron Microscopy (CEM) and Metallurgy&Materials Characterisation Facility at University of Birmingham for the support throughout the experimental investigations.

PY - 2024/3/1

Y1 - 2024/3/1

N2 - Detailed microstructural characterisation of phases present in a next generation polycrystalline Ni based superalloy after thermal exposure at 900 °C was carried out, focusing on carbides and borides. Metastable M5B3 precipitated after 32 h had a stoichiometry of (Cr0.7Mo0.2W0.1)5B3 with substitutions with Ni, Co, Nb and Ta. Fine M23C6 (a = 10.62 Å) was overgrown by metastable M5B3, as shown by rigorous TEM-SAD pattern investigation. The borides were eventually dominated by Mo rich M3B2, at the apparent expense of MC. Decomposition of MC was confirmed; it transformed sequentially to γ and then γ΄. The primary driving force for the MC decomposition was attributed to γ΄ precipitation, increasing its fraction to the thermodynamic equilibrium at 900 °C.

AB - Detailed microstructural characterisation of phases present in a next generation polycrystalline Ni based superalloy after thermal exposure at 900 °C was carried out, focusing on carbides and borides. Metastable M5B3 precipitated after 32 h had a stoichiometry of (Cr0.7Mo0.2W0.1)5B3 with substitutions with Ni, Co, Nb and Ta. Fine M23C6 (a = 10.62 Å) was overgrown by metastable M5B3, as shown by rigorous TEM-SAD pattern investigation. The borides were eventually dominated by Mo rich M3B2, at the apparent expense of MC. Decomposition of MC was confirmed; it transformed sequentially to γ and then γ΄. The primary driving force for the MC decomposition was attributed to γ΄ precipitation, increasing its fraction to the thermodynamic equilibrium at 900 °C.

KW - Superalloys

KW - Iso-thermal treatment

KW - Carbides: MC M23C6

KW - Borides: M5B3 M3B2

KW - TEM

KW - EDS

KW - Thermo-Calc software

U2 - 10.1016/j.matchar.2024.113721

DO - 10.1016/j.matchar.2024.113721

M3 - Article

SN - 1044-5803

VL - 209

JO - Materials Characterization

JF - Materials Characterization

M1 - 113721

ER -