Abstract
The pesting behavior of MoSi2 and Mo(Si,Al)2 has been examined in air at 773 K to clarify the origin and mechanism of pesting phenomena and the effect of aluminum on pesting phenomena. The initial cracks play a much more important role than the grain boundaries and the initial oxide layer in pesting. Mo and Si oxidize to amorphous Mo-Si-O simultaneously with about a 200% volume expansion. Therefore, large stress appears at the cracktips and induce many new cracks. MoO3 vaporizes from the Mo-Si-O layer on the external surface and crack surfaces causing the oxides in the initial cracks to become porous. Oxygen has a short-circuit path to enter the sample in the cracks. Therefore, the partial pressure of oxygen is sufficiently high to allow oxidation of Mo in the materials. The platelet-like MoO3 grows on the external surface and also in the cracks. Finally, the sample distintegrates into powder. Pesting of Mo(Si,Al)2 occurs in the same way, however, its rate is much lower than that of MoSi2. The role of Al is to decrease the initial crack density of the samples from the melt. Other effects of Al might be to decrease the oxygen flux toward the oxide-intermetallic interface and to increase the plasticity of the amorphous oxide being formed in the cracks.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
E. W. Lee, J. Cook, A. Khan, R. Mahapatra and J. Waldman,J. Met. 43, 54 (1991).
J. Cook, A. Khan, E. Lee and R. Mahapatra,Materials Science and Engineering A155, 183 (1992).
J. Schlichting,High Temperatures-High Pressures,14, 717 (1982).
A. K. Vasudevan and J. J. Petrovic,Materials Science and Engineering A155, 1 (1992).
P. J. Meschter,Metall. Trans. 23A, 1763 (1992).
H. J. Grabke and G. H. Meier,Oxidation of Metals 44, 147 (1995).
T. Maruyama, K. Yanagihara and K. Nagata,Corrosion Science 35, 939 (1993).
K. Yanagihara, T. Maruyama and NK. Nagata,Materials Transactions, JIM 34, 1200 (1993).
K. Yanagihara, T. Maruyama and K. Nagata,Intermetallics 3, 243 (1995).
E. Fitzer, Proc.2nd Plansee Semin. 56 (1955).
C. G. McKamey, P. F. Tortorelli, J. H. DeVan, and C. A. Carmichael,L. Mate. Res. 7, 2747 (1992).
D. A. Berztiss, R. A. Cerchiara, E. A. Gulbransen, F. S. Pettit, and G. H. Meier,Materials Science and Engineering,A155, 165 (1992).
T. C. Chou and T. G. Nieh,JOM 15 December (1993).
T. C. Chou and T. G. Nieh,Mat. Res. Symp. Proc. 288, 1993.
T. C. Chou and T. G. Nieh,Scripta Metallurgicaet Materialia,27, 1637 (1992).
T. C. Chou and T. G. Nieh,Scripta Metallurgicaet Materialia 26, 19 (1992).
T. C. Chou and T. G. Nieh,J. Mater. Res. 8, 214 (1993).
J. B. Berkowitz-Mattuck, P. E. Blackurn, and E. J. Felten,Trans. Met. Soc. AIME 233, 1093 (1965).
J. B. Berkowitz-Mattuck, M. Rossetti, and D. W. Lee,Metall. Trans. 1, 479 (1970).
A. Mueller, G. Wang, R. A. Rapp, and E. L. Courtright,J. Electrochem. Soc. 139, 1266 (1992).
K. Yanagihara, T. Maruyama, and K. Nagata,Intermetallics,4, 5133 (1996).
Y. Umakoshi, T. Sakagami, T. Hirano, and Y. Yamane,Acta Metall. 38, 909 (1990).
R. M. Aikin Jr.,Scripta Metall. 26, 1025 (1992).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yanagihara, K., Przybylski, K. & Maruyama, T. The role of microstructure on pesting during oxidation of MoSi2 and Mo(Si,Al)2 at 773 K. Oxid Met 47, 277–293 (1997). https://doi.org/10.1007/BF01668515
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01668515