Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-26T22:33:29.541Z Has data issue: false hasContentIssue false
  • English
  • Français

Thermodynamic evaluation of reaction products and layering in brazed alumina joints

Published online by Cambridge University Press:  03 March 2011

G.P. Kelkar ,
K.E. Spear  and
A.H. Carim
G.P. Kelkar
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
K.E. Spear
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
A.H. Carim
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
Get access

Abstract

The joints formed by brazing Al2O3 to itself or to a Ti-alloy (Ti-6Al-4V) with a Ag–Cu–Ti braze filler were investigated. In the brazing process, Ti in the braze alloy reduces Al2C3 to form a series of reaction products which have a layered morphology. The formation of M6X-type compounds, Ti4Cu2O or Ti3Cu3O, at the interface is characteristic of these joints. The other reaction products also belong to the Ti–Cu–O system (with the reduced Al in solution), and hence this subsystem was chosen to assess the thermodynamic stability of the joints. The Ti–Cu–O section was established experimentally at 945 °C, and activities of elements in three of the three-phase regions were estimated based on the phase boundaries of the ternary section and available binary thermodynamic data. The estimated free energies of formation of the two M6X-type compounds, Ti4Cu2O and Ti3Cu3O, are −120 kcal/mol and −122 kcal/mol, respectively. The highly negative values for the free energies of formation suggest that these compounds are thermodynamically stable. The activity data were also used to generate activity diagrams for Ti–Cu–O system. The layer sequences at the joints satisfied the stability requirements based on the ternary section and the activity diagrams, indicating that even though the interfaces formed in a matter of minutes, they were at local thermodynamic equilibrium.

Type
Articles
Information
Journal of Materials Research , Volume 9 , Issue 9 , September 1994 , pp. 2244 - 2250
Copyright
Copyright © Materials Research Society 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1Loehman, R. E. and Tomsia, A. P., Ceram. Bull. 67, 375 (1988).Google Scholar
2Kingery, W. D., J. Am, Ceram. Soc. 36, 362 (1953).CrossRefGoogle Scholar
3Okamoto, T., ISIJ Int. 30, 1033 (1990).CrossRefGoogle Scholar
4Mizuhara, H. and Heubel, E., Weld. J. 65, 43 (1986).Google Scholar
5Moorhead, A. J. and Keating, H., Weld. J. 65, 17 (1986).Google Scholar
6Standing, R. and Nicholas, M. G., J. Mater. Sci. 13, 1509 (1978).CrossRefGoogle Scholar
7Nicholas, M. G., Valentine, T. M., and Waite, M. J., J. Mater. Sci. 15, 2197 (1980).CrossRefGoogle Scholar
8Kapoor, R. R. and Eagar, T. W., J. Am. Ceram. Soc. 72, 448 (1989).CrossRefGoogle Scholar
9Santella, M. L., Horton, J. A., and Pak, J. J., J. Am. Ceram. Soc. 73, 1785 (1990).CrossRefGoogle Scholar
10Barbier, F., Peytour, C., and Revcolevschi, A., J. Am. Ceram. Soc. 73, 1582 (1990).CrossRefGoogle Scholar
11Carim, A. H., Scripta Metall. Mater. 25, 51 (1991).CrossRefGoogle Scholar
12Kelkar, G. P. and Carim, A. H., J. Am. Ceram. Soc. 76, 1815 (1993).CrossRefGoogle Scholar
13Murray, J. L. and Wreidt, H. A., in Phase Diagrams of Binary Titanium Alloys, edited by Murray, J. L. (ASM, Metals Park, OH, 1987), p. 211.Google Scholar
14Naidich, Yu. V. and Zhuravlev, V. S., Poroshk. Metall. [Sov. Powder Metall. Met. Ceram.] 12, 895 (1973).CrossRefGoogle Scholar
15Kuzumaki, T., Ariga, T., Miyamoto, Y., and Kobayashi, T., ISIJ Int. 30, 403 (1990).CrossRefGoogle Scholar
16Nicholas, M. G. and Crispin, R. M., Ceram. Eng. Sci. Proc. 10, 1602 (1989).CrossRefGoogle Scholar
17Kritsalis, P., Coudurier, L., and Eustathopoulos, N., J. Mater. Sci. 26, 3400 (1991).CrossRefGoogle Scholar
18Kuo, K., Acta Metall. 1, 301 (1953).CrossRefGoogle Scholar
19Nevitt, M. V., in Electronic Structure and Alloy Chemistry of the Transition Elements, edited by Beck, P. A. (Interscience Publishers, New York, 1963), pp. 101–178.Google Scholar
20Murray, J. L., in Phase Diagrams of Binary Titanium Alloys, editedby Murray, J. L. (ASM, Metals Park, OH, 1987), p. 80.Google Scholar
21Kubaschewski, O. and Dench, W. A., J. Inst. Met. 82, 87 (1953–54).Google Scholar
22Komarek, K. L. and Silver, M., in Thermodynamics of Nuclear Materials, edited by Eklund, S. (Proc. Symp. Thermodyn. Nucl. Mater., I. A. E. A., Vienna, Austria, 1962), p. 749.Google Scholar
23JANAF Thermochemical Tables, J. Phys. Chem. Ref. Data, Suppl. 14 (1985).Google Scholar
24Sambasivan, S., Ph.D. Thesis, Arizona State University, December 1990.Google Scholar
25van Loo, F.J.J., Prog. Solid State Chem. 20, 47 (1990).CrossRefGoogle Scholar
26Kubaschewski, O., Rev. Hautes Temper, et Refract. 3, 229–234 (1966).Google Scholar
27Loehman, R. E. and Tomsia, A. P., Acta Metall. Mater. 40 (Supplement), S75–S83 (1992).CrossRefGoogle Scholar