Influence of Cryomilling on Microstructure, Phase Stability and Oxidation Behavior of NiCrAlY Bond Coat in Thermal Barrier Coatings: Experimentation and Mechanistic Investigation

Article Preview

Abstract:

Improved thermal cycling lifetime has been observed in thermal barrier coatings (TBCs) with cryomilled NiCrAlY bond coat. To understand this improved behavior, a robust experimental investigation is coupled with mechanistic explanations to describe the influence of cryomilling on microstructure, phase stability and oxidation behavior of the bond coat. It is found that cryomilling results in two significant changes in the NiCrAlY bond coat: unintentional Fe additions and creation of a homogeneous distribution of ultrafine oxide/nitride dispersoids. Through extensive microstructural analysis combined with computational simulation using Thermo-Calc® software, it is determined that the presence of Fe stabilizes the high temperature γ and β phases in the NiCrAlY bond coat, corresponding to a decrease in the transformation temperature. The results are explained on the basis of the Gibbs free energy for the individual phases. Characterization of the thermally grown oxide (TGO) in TBCs after isothermal oxidation with rigorous statistical evaluation indicates that the TGOs in the TBCs with the cryomilled bond coats are more uniform in thickness and slower growing. Both behaviors are attributed to the more homogeneous distribution of oxide dispersoids, which are a direct result of the cryomilling, yet remain stable after extensive thermal exposure.

You might also be interested in these eBooks

Info:

Periodical:

Materials Science Forum (Volumes 654-656)

Pages:

1940-1943

Citation:

Online since:

June 2010

Export:

Price:

[1] J. R. Nicholls, N. J. Simms, W. Y. Chan, H. E. Evans, Surface and Coatings Technology 149 (2002) 236-244.

DOI: 10.1016/s0257-8972(01)01499-2

Google Scholar

[2] K. W. Schlichting, N. P. Padture, E. H. Jordan, M. Gell, Materials Science and Engineering A 342 (2003) 120-130.

Google Scholar

[3] E. Tzimas, H. Müllejans, S. D. Peteves, J. Bressers, W. Stamm, Acta Materialia 48 (2000) 4699-4707.

DOI: 10.1016/s1359-6454(00)00260-3

Google Scholar

[4] H. Echsler, V. Shemet, M. Schütze, L. Singheiser, W. Quadakkers, Journal of Materials Science 41 (2006) 1047-1058.

DOI: 10.1007/s10853-005-3639-3

Google Scholar

[5] A. Rabiei, A. G. Evans, Acta Materialia 48 (2000) 3963-3976.

Google Scholar

[6] A. G. Evans, D. R. Mumm, J. W. Hutchinson, G. H. Meier, F. S. Pettit, Progress in Materials Science 46 (2001) 505-553.

DOI: 10.1016/s0079-6425(00)00020-7

Google Scholar

[7] A. G. Evans, D. R. Clarke, C. G. Levi, Journal of the European Ceramic Society 28 (2008) 1405-1419.

Google Scholar

[8] T. Xu, S. Faulhaber, C. Mercer, M. Maloney, A. Evans, Acta Materialia 52 (2004) 1439-1450.

Google Scholar

[9] A. K. Ray, N. Roy, K. M. Godiwalla, Bulletin of Materials Science 24 (2001) 203-209.

Google Scholar

[10] B. Hazel, J. Rigney, M. Gorman, B. Boutwell, R. Darolia, Proceedings of the International Symposium on Superalloys (2008) 753-760.

DOI: 10.7449/2008/superalloys_2008_753_760

Google Scholar

[11] B. A. Pint, I. G. Wright, W. Y. Lee, Y. Zhang, K. Prüßner, K. B. Alexander, Materials Science and Engineering A 245 (1998) 201-211.

DOI: 10.1016/s0921-5093(97)00851-4

Google Scholar

[12] F. Tang, L. Ajdelsztajn, G. E. Kim, V. Provenzano, J. M. Schoenung, Materials Science and Engineering: A 425 (2006) 94-106.

Google Scholar

[13] J. A. Picas, A. Forn, L. Ajdelsztajn, J. Schoenung, Powder Technology 148 (2004) 20-23.

DOI: 10.1016/j.powtec.2004.09.015

Google Scholar

[14] F. Tang, L. Ajdelsztajn, J. M. Schoenung, Scripta Materialia 51 (2004) 25-29.

Google Scholar

[15] F. Tang, L. Ajdelsztajn, J. M. Schoenung, Oxidation of Metals 61 (2004) 219-238.

Google Scholar

[16] L. Ajdelsztajn, F. Tang, G. E. Kim, V. Provenzano, J. M. Schoenung, Journal of Thermal Spray Technology 14 (2005) 23-30.

DOI: 10.1361/10599630522693

Google Scholar

[17] L. Ajdelsztajn, D. Hulbert, A. Mukherjee, J. M. Schoenung, Surface and Coatings Technology 201 (2007) 9462-9467.

DOI: 10.1016/j.surfcoat.2007.03.054

Google Scholar

[18] E. J. Lavernia, B. Q. Han, J. M. Schoenung, Materials Science and Engineering: A 493 (2008) 207-214.

Google Scholar

[19] D. R. G. Achar, R. Munoz-Arroyo, L. Singheiser, W. J. Quadakkers, Surface and Coatings Technology 187 (2004) 272-283.

DOI: 10.1016/j.surfcoat.2004.02.018

Google Scholar

[20] K. Ma, F. Tang, J. M. Schoenung, Acta Materialia 58 (2010) 1518-1529.

Google Scholar

[21] J. O. Andersson, T. Helander, L. Höglund, P. Shi, B. Sundman, Calphad 26 (2002) 273-312.

DOI: 10.1016/s0364-5916(02)00037-8

Google Scholar