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What Determines the Peak-Temperature in Binary Ni3Al?

Published online by Cambridge University Press:  22 February 2011

C. Rentenberger Karnthaler  and
H.P. Karnthaler
C. Rentenberger Karnthaler
Affiliation:
Inst. f. Festkörperphysik, University of Vienna, Boltzmanng. 5, A-1090 Wien, Austria.
H.P. Karnthaler
Affiliation:
Inst. f. Festkörperphysik, University of Vienna, Boltzmanng. 5, A-1090 Wien, Austria.
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Abstract

In Ni3Al alloys the yield stress increases with increasing temperature up to a maximum stress, reached at the temperature TP. Below TP glide occurs on primary octahedral planes whereas above TP glide on primary cube planes is dominating. Therefore this change of glide planes was considered to determine TP.

TEM investigations were carried out to study the mechanisms that control TP in Ni3Al specimens with [001] compression axis. In this case no shear stresses are acting on any of the cube glide systems. The TEM results show a pronounced change of the dislocation structure on the {111} glide planes below and above the peak. The breakdown of the barriers (locked screw dipoles) starts when the diffusion is high enough to facilitate their annihilation. The dynamic recovery of the locked screws occurs by multiple cross-slip via octahedral planes. It is proposed that, in this and other ordered alloys, the value of TP is diffusion controlled.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 364: Symposium L – High-Temperature Ordered Intermetallic Alloys–VI , 1994 , 689
Copyright
Copyright © Materials Research Society 1995

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References

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