Abstract
High-resolution transmission electron microscopy and high-angle annular dark-field imaging were used to study differences in the interfacial and compositional characteristics between the plate-shaped σ and γ phases in a Ni-based single-crystal superalloy. An atomic structural model of the interface between the σ and γ phases that includes a step was proposed. The σ phase exhibits the following relationship with the matrix: [0 0 1] γ//[112̄] σ, (2̄20) γ//(1̄10) σ, (2̄2̄0) γ//(1 1 1) σ, [0 1 1] γ//[1 1 0] σ, (11̄1) γ//(001̄) σ. The compositional characteristics of the σ phase indicate that it is rich in high-Z elements (Z is the atomic number), especially the alloying element rhenium (Re). The impurity formation energies for the σ and γ phases doped with Re in different sublattices were investigated using the first-principles method based on the density functional theory. The bonding characteristics of the undoped and doped σ and γ phases were analyzed with the valence charge densities and the density of states. The results indicate that the alloying element Re, with a large atomic size, substitutes the W atom preferentially, owing to the nature of the bonding and the interstitial spaces in the crystal structure.
Original language | English |
---|---|
Pages (from-to) | 6631-6640 |
Number of pages | 10 |
Journal | Acta Materialia |
Volume | 60 |
Issue number | 19 |
DOIs | |
Publication status | Published - 2012 Nov |
Keywords
- First-principles calculations
- High-resolution transmission electron microscopy
- Ni-based single-crystal superalloys
- Rhenium (Re)
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys