|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Computational Thermodynamics and Kinetics
||First-principles Study of Interfacial Stability and Solute Partitioning in Al-alloy Precipitates
||Kyoungdoc Kim, Chris Wolverton
|On-Site Speaker (Planned)
To understand the primary strengthening mechanisms of precipitates in commercial Al-Cu-Mg-Si alloys, we performed atomic-scale density functional theory (DFT) calculations of the stability of the interfacial structure, solute partitioning, and defect properties of two commonly-occurring precipitates, Al2Cu (θ') and Al3Cu2Mg9Si7 (Q). We find: (i) The recently-proposed occupancy of interstitial Cu atoms at the coherent (001) θ'//(001) Al interface thermodynamically increases interfacial stability, and changes solute segregation behavior. (ii) Simple native point defect (i.e., vacancies and anti-sites) thermodynamics can partially explain Q-phase off-stoichiometry. (iii) Calculated solute-partitioning energies of common solutes allow us to define general rules for site-preference in Q-phase in terms of electronic structure and atomic radius. (iv) For the (11-20) Q // (510) Al interface, we survey various terminations and orientations and derive a low-energy structure. We find Cu is the nearest atom to the interface, which is in agreement with previous literature on Cu interfacial segregation.
||Planned: A print-only volume