A first-principles study of the β” -phase in Al-Mg-Si alloys TeX Export

@article{derlet02, abstract = {Al-Mg-Si alloys gain an increase in strength due to small precipitates of Mg and Si formed from the solid-solution phase, where maximum hardness arises from a combination of a large number of fully coherent Guinier-Preston (GP)\~{}1 zones and semi-coherent GP\~{}2 zones (the \β'' -Mg\$\_{5}\$Si\$\_{6}\$ phase), both existing as needle-like structures. In the present work we investigate the nature of bonding within the equivalent bulk structure of the \β'' -phase, using the density functional theory technique. In particular we investigate the presence of covalent bonding between Si using the calculated charge-density/transfer distributions of the structure. In addition we find small residual Hellmann-Feynman forces on the atoms, and accordingly relax the structure and find a more symmetric structure in terms of geometry and charge density. We find also that the converged structure is stable against atomic position perturbations that break the inversion and mirror plane symmetries of the C 2/ m \β'' -phase. Finally we investigate a face-centred-cubic array of only Mg and Si atoms - a candidate model for the GP\~{}1 phase, from which the \β'' -structure may be recovered by a simple transformation and subsequent atomic relaxation.}, author = {Derlet, P. M. and Andersen, S. J. and Marioara, C. D. and Fr\o{}seth, A.}, citeulike-article-id = {449657}, citeulike-linkout-0 = {http://stacks.iop.org/0953-8984/14/4011}, journal = {Journal of Physics: Condensed Matter}, keywords = {6082, bibtex-import, gp, hardening, microstructure, tem}, number = {15}, pages = {4011--4024}, pdf = {derlet02.pdf}, posted-at = {2005-12-25 12:44:49}, priority = {2}, title = {A first-principles study of the \β'' -phase in Al-Mg-Si alloys}, url = {http://stacks.iop.org/0953-8984/14/4011}, volume = {14}, year = {2002} }

TY - JOUR ID - derlet02 L3 - citeulike-article-id:449657 N2 - Al-Mg-Si alloys gain an increase in strength due to small precipitates of Mg and Si formed from the solid-solution phase, where maximum hardness arises from a combination of a large number of fully coherent Guinier-Preston (GP)~1 zones and semi-coherent GP~2 zones (the \β'' -Mg$_{5}$Si$_{6}$ phase), both existing as needle-like structures. In the present work we investigate the nature of bonding within the equivalent bulk structure of the \β'' -phase, using the density functional theory technique. In particular we investigate the presence of covalent bonding between Si using the calculated charge-density/transfer distributions of the structure. In addition we find small residual Hellmann-Feynman forces on the atoms, and accordingly relax the structure and find a more symmetric structure in terms of geometry and charge density. We find also that the converged structure is stable against atomic position perturbations that break the inversion and mirror plane symmetries of the C 2/ m \β'' -phase. Finally we investigate a face-centred-cubic array of only Mg and Si atoms - a candidate model for the GP~1 phase, from which the \β'' -structure may be recovered by a simple transformation and subsequent atomic relaxation. IS - 15 JF - Journal of Physics: Condensed Matter EP - 4024 TI - A first-principles study of the \β'' -phase in Al-Mg-Si alloys VL - 14 SP - 4011 KW - 6082 KW - bibtex-import KW - gp KW - hardening KW - microstructure KW - tem AU - Derlet, PM AU - Andersen, SJ AU - Marioara, CD AU - Fr\o{}seth, A PY - 2002/// UR - http://stacks.iop.org/0953-8984/14/4011 ER -