Creep strengths and ductilities of boron-doped nickel aluminides are significantly improved by small additions of hafnium. Since creep failure in these alloys proceeds by growth and coalescence of grain boundary cavities, effects of Hf additions on the compositions of grain boundaries and creep cavity surfaces were examined using Auger electron spectroscopy (AES). In order to facilitate intergranular fracture in the AES analysis chamber, gage sections from creep specimens were hydrogen charged and copper plated. Grain boundaries in crept specimens were not flat, and the grains did not exhibit a normal polyhedral appearance. The overall levels of boron detected on the fracture surfaces of the creep specimens were significantly higher than those from uncrept specimens. Additionally, boron was found to segregate more strongly to the grain boundaries while higher concentrations of residual sulfur and phosphorus were detected on the cavity surfaces in both alloys. These results are discussed in terms of the effects of impurity segregation on high temperature grain boundary cavitation.
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C.T. Liu, C.L. White, C.C. Koch and E.H. Lee, in Proceedings of the Symposium on High Temperature Materials Chemistry II, edited by Z.A. Munir and D. Cubicciotti (The Electrochemical Soc. Proc. 83-7, Pennington, NJ 1983) pp. 32-41.
C.T. Liu, C.L. White, and J.A. Horton, Acta Metall, 33 (2), 213-229 (1985).
C.T. Liu, Proc. Symp. High-Temperature Alloy Theory and Design, Bethesda, Md, April 9-11 (1984).
C.T. Liu and C.L.White in High Temperature Ordered Intermetallic Alloys, edited by C.C. Koch, C.T. Liu and N.S. Stoloff (Mat. Res. Soc. Proc. 39, Pittsburgh, PA 1985) pp. 365-380.
A. Choudhury, C.L. White and C.R. Brooks, Scr. Metall. 20,1061-1066 (1986).
L.E. Davis, N.C. MacDonald, P.W. Palmberg, G.E. Riach and R.E. Weber, Handbook of Auger Electron Spectroscopy, 2nd ed. (Physical Electronics Industries, Eden Prairie, Mn 1976) pp. 1-12, 23,57,61,93,207.
M. Takeyama and C.T. Liu, Acta Metall, 36 (5), 1241-1249 (1988).
NJ. Grant, in Fracture, An Advanced Treatise, Vol. III, edited by H. Liebowitz (Academic Press, New York, 1971) pp.483-533.
M.H. Yoo, C.L. White and H. Trinkaus, in Flow and Fracture at Elevated Temperatures, edited by R. Raj (ASM Mat. Sci. Sem., Metals Park, OH 1983) pp.349-382.
H.E. Collins and P.G. Shewmon, Trans. TMS-AIME, 236,1354-1360 (1966).
L.E. Murr, Interfacial Phenomena in Metals and Alloys, (Addison Wesley, Reading, MA 1975), pp. 31-75.
C.L. White, R.A. Padgett, C.T. Liu and S.M. Yalisove, Scr. Metall., 18, 1417-1420 (1985).
C.L. White, C.T. Liu and R.A. Padgett, Acta Metall., 36 (8), 2229-2238 (1988).
D. McLean, Grain Boundaries in Metals, (Oxford, Clarendon Press, 1957) pp. 116-149.
J.P. Hirth and J.R. Rice, Metall. Trans. A, 11A, 1501-1511 (1980).
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Au-Yeung, P.H., Lukowski, J.T. & White, C.L. Grain Boundary and Cavity Surface Segregation in Crept Ni3Al + 0.2at% B AND Ni3 (AI,Hf) + 0.2at% B. MRS Online Proceedings Library 133, 517 (1988). https://doi.org/10.1557/PROC-133-517