Abstract
In this paper we describe the structure and formation of a new intermetallic phase in the Cu-Al system, which has not been reported before. The phase was found in Cu/Al bilayer films, which were deposited at room temperature on (0001) sapphire substrates using molecular beam epitaxy. The interfacial intermetallic phase is 8 nm thick, and possesses a hexagonal close-packed structure. The lattice parameters of the phase gradually increase from the near-Cu-side to the near-Al-side. In parallel with the described lattice expansion, the chemical composition of the interlayer also varies from 27 to 58 Al at.% from the near-Cu-side to the near-Al-side. The formation and microstructural characteristics of this new phase are explained by Hume-Rothery laws and Shockley partial dislocations. In addition, in-situ heating experiments were performed in a transmission electron microscope at ∼600°C to investigate the thermodynamic stability of this new Cu-Al intermetallic phase. During annealing the intermetallic layer disappears and other known equilibrium intermetallic phases develop. This indicates that this new hexagonal close-packed CuAl intermetallic phase is metastable.
Original language | English |
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Pages (from-to) | 692-699 |
Number of pages | 8 |
Journal | International Journal of Materials Research |
Volume | 98 |
Issue number | 8 |
DOIs | |
State | Published - Aug 2007 |
Externally published | Yes |
Keywords
- Al
- Cu
- Interlayer
- Intermetallic phase
- TEM