An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy
This paper investigates the β-phase coarsening behaviour during isothermal heat treatment of free-standing CoNiCrAlY (Co-31.7%Ni-20.8%Cr-8.1%Al-0.5%Y, all in wt%) coatings prepared by high velocity oxy-fuel (HVOF) thermal spraying. The microstructure of the coatings was characterised using scanning...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Published: |
Elsevier
2017
|
| Subjects: | |
| Online Access: | https://eprints.nottingham.ac.uk/40393/ |
| _version_ | 1848796045716226048 |
|---|---|
| author | Chen, H. Si, Y.Q. McCartney, D.G. |
| author_facet | Chen, H. Si, Y.Q. McCartney, D.G. |
| author_sort | Chen, H. |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | This paper investigates the β-phase coarsening behaviour during isothermal heat treatment of free-standing CoNiCrAlY (Co-31.7%Ni-20.8%Cr-8.1%Al-0.5%Y, all in wt%) coatings prepared by high velocity oxy-fuel (HVOF) thermal spraying. The microstructure of the coatings was characterised using scanning electron microscopy with energy dispersive X-ray (EDX) analysis and electron backscatter diffraction (EBSD). It comprises a two phase structure of fcc γ-Ni matrix and bcc β-NiAl precipitates. The volume fraction of the γ-Ni and the β-NiAl phases were measured to be around 70% and 30% respectively, with grain sizes varying largely from 0.5 to 2 μm for both phases. Isothermal heat treatments of the free-standing coatings were carried out at 1100 C for times up to 250 h. The β-phase coarsening behaviour during isothermal heat treatments was analysed by quantitative metallography. It is shown that the coarsening behaviour of β phase in the CoNiCrAlY alloy followed the classical Lifshitz-Slyozov-Wagner (LSW) theory of Ostwald ripening. By incorporating a dimensionless factor which correlates with volume fraction of the β phase, a modified LSW model coupled with formulaic interfacial energy and effective diffusion coefficient of the CoNiCrAlY alloy was utilised to interpret the coarsening behaviour of the β phase. The coarsening rate coefficient obtained from the modified LSW model shows good agreement with the corresponding experimental result. |
| first_indexed | 2025-11-14T19:41:45Z |
| format | Article |
| id | nottingham-40393 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| last_indexed | 2025-11-14T19:41:45Z |
| publishDate | 2017 |
| publisher | Elsevier |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-403932020-05-04T18:36:01Z https://eprints.nottingham.ac.uk/40393/ An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy Chen, H. Si, Y.Q. McCartney, D.G. This paper investigates the β-phase coarsening behaviour during isothermal heat treatment of free-standing CoNiCrAlY (Co-31.7%Ni-20.8%Cr-8.1%Al-0.5%Y, all in wt%) coatings prepared by high velocity oxy-fuel (HVOF) thermal spraying. The microstructure of the coatings was characterised using scanning electron microscopy with energy dispersive X-ray (EDX) analysis and electron backscatter diffraction (EBSD). It comprises a two phase structure of fcc γ-Ni matrix and bcc β-NiAl precipitates. The volume fraction of the γ-Ni and the β-NiAl phases were measured to be around 70% and 30% respectively, with grain sizes varying largely from 0.5 to 2 μm for both phases. Isothermal heat treatments of the free-standing coatings were carried out at 1100 C for times up to 250 h. The β-phase coarsening behaviour during isothermal heat treatments was analysed by quantitative metallography. It is shown that the coarsening behaviour of β phase in the CoNiCrAlY alloy followed the classical Lifshitz-Slyozov-Wagner (LSW) theory of Ostwald ripening. By incorporating a dimensionless factor which correlates with volume fraction of the β phase, a modified LSW model coupled with formulaic interfacial energy and effective diffusion coefficient of the CoNiCrAlY alloy was utilised to interpret the coarsening behaviour of the β phase. The coarsening rate coefficient obtained from the modified LSW model shows good agreement with the corresponding experimental result. Elsevier 2017-02-03 Article PeerReviewed Chen, H., Si, Y.Q. and McCartney, D.G. (2017) An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy. Journal of Alloys and Compounds . ISSN 1873-4669 HVOF spraying; MCrAlY; β-phase; Coarsening; Heat treatment; Diffusion http://www.sciencedirect.com/science/article/pii/S0925838817304176 doi:10.1016/j.jallcom.2017.02.002 doi:10.1016/j.jallcom.2017.02.002 |
| spellingShingle | HVOF spraying; MCrAlY; β-phase; Coarsening; Heat treatment; Diffusion Chen, H. Si, Y.Q. McCartney, D.G. An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy |
| title | An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy |
| title_full | An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy |
| title_fullStr | An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy |
| title_full_unstemmed | An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy |
| title_short | An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy |
| title_sort | analytical approach to the β-phase coarsening behaviour in a thermally sprayed conicraly bond coat alloy |
| topic | HVOF spraying; MCrAlY; β-phase; Coarsening; Heat treatment; Diffusion |
| url | https://eprints.nottingham.ac.uk/40393/ https://eprints.nottingham.ac.uk/40393/ https://eprints.nottingham.ac.uk/40393/ |