Abstract
The structure and mobility of superdislocations in Ir3X (X = Ti, Zr, Hf, V, Nb, Ta) with L12 structure were investigated in the framework of the modified Peierls-Nabarro (PN) model with first-principles generalized stacking fault energetics calculated using the all-electron full-potential linearized augmented plane wave method (FLAPW). Superlattice intrinsic stacking fault (SISF)-bound superdislocations (Kear splitting scheme) are strongly preferred energetically in Ir3V, Ir3Nb, and Ir3Ta, whereas antiphase boundary (APB)-bound superdislocations (Shockley splitting scheme) are predicted in Ir3Ti, Ir3Zr, and Ir3Hf. Because APB-bound superdislocations are considered responsible for the yield stress anomaly, our results predict that positive yield stress temperature dependence could only be expected in Ir3Ti, Ir3Zr, and Ir3Hf, and a negative one in Ir3V, Ir3Nb, and Ir3Ta. The connection of the mechanical behavior of the Ir3X alloys with the L12 → D019 structural instability is established and the electronic origins of this instability are analyzed.
Original language | English (US) |
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Pages (from-to) | 559-566 |
Number of pages | 8 |
Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
Volume | 36 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2005 |
Funding
This work was supported by the AFOSR (under Grant No. FA9550-04-1-0013), computer time grants at NAVO, NCSA, and SDSC, and in part by the Russian Basic Research Foundation (Grant No. 03-02-16811-A).
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys