The ductility of preoxidized Ni3Al (Ni-23Al-0.5Hf-0.2B, at.%) specimens with various grain sizes (17∼193 μm) was evaluated by means of tensile tests at 600 and 760°C in vacuum. It was found that the preoxidation does not affect the ductility of the finest-grained material at either temperature, whereas it causes severe embrittlement in the largest-grained material, especially at 760°C. A continuous, thin Al-rich oxide layer, which forms on the fine-grained samples, protects the underlying alloy from oxygen penetration, preventing any loss of ductility, whereas the nickel-rich oxide which forms on the large-grained samples allows oxygen to penetrate along grain boundaries, causing severe embrittlement. The grain boundaries act as short-circuit paths for rapid diffusion of aluminum atoms from the bulk to the surfaces, and this is responsible for the difference in oxidation behavior between fine- and large-grained materials. The embrittlement of large-grained samples can be eliminated through control of oxide formation on Ni3Al surfaces.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
C. T. Liu, C. L. White and E. H. Lee, Scripta Metall. 19, 1247 (1985).
C. T. Liu and C. L. White, Acta Metall. 35, 643 (1987).
A. I. Taub, K. -M. Chang and C. T. Liu, Scripta Metall. 20, 1618 (1986).
M. Takeyama and C. T. Liu, Acta Metall. 36, 1241 (1988).
T. P. Weihs, V. Zinoviev, D. V. Viens and E. M. Schulson, Acta Metall. 35, 1109(1987).
A. Choudhury, C. L. White and C. R. Brooks, Scripta Metall. 20, 1061 (1986).
L. E. Davis, N. C. MacDonald, P. W. Palmberg, G. E. Riach and R. E. Weber, Handbook of Auger Electron Spectroscopy, Perkin-Elmer Corporation, Eden Prairie, Minn (1978).
M. Takeyama and C. T. Liu, unpublished results, Oak Ridge National Laboratory (1988).
C. S. Giggins and F. S. Pettit, TMS-AIME 245, 2509 (1969).
G. J. Yurek, D. Eisen and A. Garratt-Reed, Metall. Trans. A 13A, 473 (1982).
F. S. Pettit, TMS-AIME 239, 1296 (1967).
About this article
Cite this article
Takeyama, M., Liu, C.T. Effect of Preoxidation and Grain Size on Ductility of a Boron-Doped Ni3Al at Elevated Temperatures. MRS Online Proceedings Library 133, 293 (1988). https://doi.org/10.1557/PROC-133-293