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Elastic anisotropy and phonon focusing for tetragonal crystals: Application to γ-TiAl
- Source :
- Computational Materials Science. 118:117-123
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- A theoretical formalism to investigate the elastic anisotropy and phonon focusing for tetragonal crystals is described in detail in this paper. This is applied for γ-TiAl and both of the numerical indicators and the three dimensional images of elastic anisotropy are derived. The percentage of bulk and shear anisotropies indicate γ-TiAl exhibits relatively high degree of anisotropy in shear but small anisotropy in compressibility. Anisotropy indexes A ∗ and A U demonstrate γ-TiAl possesses high degree of anisotropy, and this feature is also reflected in the three dimensional Young’s modulus, shear modulus and Poisson’s ratio. Three slowness surfaces are constructed for γ-TiAl to investigate the phonon focusing patterns, and the group velocity surfaces are also obtained to gain more insight into the elastic anisotropy. Due to elastic anisotropy, both of the slowness surfaces and the group velocity surfaces are nonspherical. The anisotropy is highest for slow transverse mode, and then followed by fast transverse mode and longitudinal mode. Interestingly, only transverse phonons cause caustics for γ-TiAl. Furthermore, the phase velocity and group velocity are not collinear for transverse mode in some directions, resulting in cuspidal edges along these directions in the group velocity surfaces.
- Subjects :
- Materials science
General Computer Science
Condensed matter physics
Phonon
business.industry
General Physics and Astronomy
02 engineering and technology
General Chemistry
021001 nanoscience & nanotechnology
01 natural sciences
Transverse mode
Shear modulus
Longitudinal mode
Computational Mathematics
Transverse plane
Optics
Mechanics of Materials
0103 physical sciences
Group velocity
General Materials Science
Phase velocity
010306 general physics
0210 nano-technology
business
Anisotropy
Subjects
Details
- ISSN :
- 09270256
- Volume :
- 118
- Database :
- OpenAIRE
- Journal :
- Computational Materials Science
- Accession number :
- edsair.doi...........f414918feb81e70c051c14325e7328f5