Hostname: page-component-84b7d79bbc-dwq4g Total loading time: 0 Render date: 2024-07-26T12:01:44.589Z Has data issue: false hasContentIssue false
  • English
  • Français

Vacancy Mobility in Nickel Aluminide Versus Composition

Published online by Cambridge University Press:  10 February 2011

Bin Bai ,
Jiawen Fan  and
Gary S. Collins
Bin Bai
Affiliation:
Department of Physics, Washington State University, Pullman, WA 99164
Jiawen Fan
Affiliation:
Department of Physics, Washington State University, Pullman, WA 99164
Gary S. Collins
Affiliation:
Department of Physics, Washington State University, Pullman, WA 99164, collins@wsu.edu
Get access

Abstract

The fractional concentration of Ni-vacancies in NiAl at high temperature has been determined for compositions between 50 and 53 at.% Ni from measurements using perturbed angular correlation of gamma rays (PAC). The vacancies were detected by quadrupole interactions induced at nearby 111In/Cd impurity probes present on the Al sublattice in high dilution. One set of measurements was made at high temperature. A second set made after rapid quenching exhibited an enhancement of Ni-vacancy site fractions that is attributed to diffusion and trapping of vacancies during quenching. The composition dependence of the enhancement was analyzed assuming that the enhancement is proportional to the root-mean-square diffusion length during quenching. The experimental dependence on composition is found to be consistent with bulk diffusion data. The methodology developed clarifies how local environments of impurity probes are modified during rapid quenching. In addition, it is shown that there is an enormous increase in the mobility of vacancies with increasing deviation of the composition from stoichiometry. Diffusion mechanisms that can explain the data trends are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 527: Symposium Z – Diffusion Mechanisms in Crystalline Materials , 1998 , 203
Copyright
Copyright © Materials Research Society 1998

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

1. Kao, C.R., Lee, Sungtae and Chang, Y.A., Mat. Sci. & Engin. A192/193, 965 (1995).Google Scholar
2. Philibert, Jean, Atom movements: diffusion and mass transport in solids, translated by Rothman, Steven J. (Les Editions de Physique, 1991), pp. 187–191.Google Scholar
3. Mishin, Yuri and Farkas, Diana, Phil, Mag. A75, 169 and 187 (1997).Google Scholar
4. Chang, Y. Austin and Neumann, Joachim P., Prog. Solid State Chem. 14 221 (1982) and references therein.Google Scholar
5. Bai, Bin, Ph.D. dissertation, Washington State University 1997 (unpublished).Google Scholar
6.The first three mechanisms all involve very low equilibrium concentrations of Al-vacancies present, for example, due to thermal formation of Schottky vacancy pairs.Google Scholar
7. Recknagel, E., Schatz, G. and Wichert, Th., in Hyperfine Interactions of Radioactive Nuclei, ed. Christiansen, J., p. 133 (Springer, 1983).Google Scholar
8. Collins, G.S., Shropshire, S.L. and Fan, J., Hyperfine Interactions 62 1 (1990).Google Scholar
9. Fan, J. and Collins, G.S., Hyperfine Interactions 60 655 (1990).Google Scholar
10. Fan, J., Ph.D. dissertation, Washington State University, 1992 (unpublished), and ref. [8*].Google Scholar
11. Collins, G.S., Fan, J. and Bai, B., in Structural Intermetallics 1997, ed. Nathal, M.V. et al., (The Minerals, Metals and Materials Society, 1997), p. 43.Google Scholar
12.The measurement of the binding enthalpy was made in an unusual low-temperature regime in NiAl extending between about 350 and 650 C in which quenched-in excess Ni-vacancies are able to diffuse without annealing out (cf. ref. 10 and 11).Google Scholar
13. Shankar, S. and Seigle, L.L., Metallurgical Transactions 9A, 1467 (1978).Google Scholar