Abstract
This paper investigates the strength response of Ir-xHf-yNb alloys (x = 3, 4, 5, 8, 9, 10 at.%, and y = 5, 6, 7, 11, 13, 15 at.%) with a dual-phase fcc/L1 2 microstructure at room and high temperatures. The experimental strength at 1950 °C was compared with that obtained by the rule of mixture. The results showed that in the fcc/L1 2 structure the fcc phase always shows higher strength than the L1 2 phase, at both room and high temperatures. A dual-phase fcc/L1 2 microstructure with different fcc to L1 2 fraction ratio formed when Hf and Nb contents in the Ir-xHf-yNb ternary alloys were larger than 3 at.% and 5 at.%, respectively, and the pure L1 2 microstructure was obtained at 10 at.% Hf and 15 at.% Nb. The Ir-5Hf-7Nb alloy, possessing an fcc-dominant microstructure in which the optimization fcc fraction is about 78%, has an outstanding 0.2% yield compressive strength of 270 MPa even at 1950 °C. This ultra-high strength is attributed to strong interface hardening by the large lattice misfit between the fcc and L1 2 phases. The failure mode of the Ir-Hf-Nb ternary alloys is by debonding of the grain boundary.
Original language | English |
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Pages (from-to) | 145-150 |
Number of pages | 6 |
Journal | Intermetallics |
Volume | 32 |
DOIs | |
Publication status | Published - 2013 Jan 1 |
Externally published | Yes |
Keywords
- A. Intermetallics
- A. Ternary alloy systems
- B. Phase identification
- D. Microstructure
- E. Mechanical properties, theory
ASJC Scopus subject areas
- Chemistry(all)
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry