Abstract
The thermodynamic properties of solid solutions with body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed (hcp) structures in the Al-TM (TM = Ti, Zr and Hf) systems are calculated from first-principles using cluster expansion (CE), Monte-Carlo simulation and supercell methods. The 32-atom special quasirandom structure (SQS) supercells are employed to compute properties at 25, 50 and 75 at.% TM compositions, and 64-atom supercells have been employed to compute properties of alloys in the dilute concentration limit (one solute and 63 solvent atoms). In general, the energy of mixing (ΔmE) calculated by CE and dilute supercells agree very well. In the concentrated region, the ΔmE values calculated by CE and SQS methods also agree well in many cases; however, noteworthy discrepancies are found in some cases, which we argue originate from inherent elastic and dynamic instabilities of the relevant parent lattice structures. The importance of short-range order on the calculated values of ΔmE for hcp Al-Ti alloys is demonstrated. We also present calculated results for the composition dependence of the atomic volumes in random solid solutions with bcc, fcc and hcp structures. The properties of solid solutions reported here may be integrated within the CALPHAD formalism to develop reliable thermodynamic databases in order to facilitate: (i) calculations of stable and metastable phase diagrams of binary and multicomponent systems, (ii) alloy design, and (iii) processing of Al-TM-based alloys.
Original language | English (US) |
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Pages (from-to) | 3202-3221 |
Number of pages | 20 |
Journal | Acta Materialia |
Volume | 56 |
Issue number | 13 |
DOIs | |
State | Published - Aug 2008 |
Funding
This research was supported by the US Department of Energy, Office of Basic Energy Sciences, under Contract Nos. DE-FG02-02ER45997 (G.G.) and DE-FG02-01ER45910 (A.v.d.W. and M.A.) at Northwestern, and DE-FG02-06ER46282 (M.A.) at UC Davis. In addition, this material is based upon work supported by the National Science Foundation under the following NSF programs: Partnerships for Advanced Computational Infrastructure, Distributed Terascale Facility (DTF) and Terascale Extensions: Enhancements to the Extensible Terascale Facility. Specific to NSF programs, two of us (G.G. and A.v.d.W.) have utilized Itanium clusters as a part of TeraGrid sites at the University of Illinois at Urbana-Champaign and at San Diego Supercomputing Center. One of us (G.G.) would like to thank Prof. I.A. Abrikosov, Linköping University, Sweden, for fruitful discussions. The authors thank Prof. M. Widom, Carnegie Mellon University, for sharing his partial correlation function calculation code.
Keywords
- Ab initio electron theory
- Cluster expansion
- Phase stability
- Special quasirandom structure (SQS)
- Thermodynamics
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys