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Atomic Defects in Intermetallic Compounds and Diffusion Processes

Published online by Cambridge University Press:  10 February 2011

H.-E. Schaefer
Affiliation:
Universität Stuttgart, Institut für Theoretische und Angewandte Physik, Pfaffenwaldring 57, D-70569 Stuttgart, Germany, e-mail:[email protected]
K. Frenner
Affiliation:
Universität Stuttgart, Institut für Theoretische und Angewandte Physik, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
R. Würschum
Affiliation:
Universität Stuttgart, Institut für Theoretische und Angewandte Physik, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
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Abstract

For the understanding of the properties of the technically important intermetallic compounds as transition metal aluminides and silicides the understanding of atomic defect properties is pivotal. From recent positron lifetime studies high or low values for the effective vacancy formation enthalpy were found for close-packed or for more open-structured bcc type compounds, respectively, which can be well understood theoretically. In B2-FeAl the vacancy migration enthalpy could be additionally derived at high temperatures from vacancy equilibration processes. It is shown here by a study on B2-FeAl in comparison to the positron annihilation experiments that the thermal formation and migration of defects can be specifically investigated by time-dependent length-change experiments at high temperatures by the defect equilibration behavior after temperature changes. With the present data on vacancy formation and migration the wide variation of the transition-metal self-diffusivities in intermetallic compounds can be understood.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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References

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