TY - JOUR
T1 - Predicting metastable phase boundaries in Al-Cu alloys from first-principles calculations of free energies
T2 - The role of atomic vibrations
AU - Ravi, C.
AU - Wolverton, C.
AU - Ozoliņš, V.
PY - 2006/3/1
Y1 - 2006/3/1
N2 - Metastable precipitate phase boundaries are difficult to ascertain experimentally and yet are important for controlling the microstructure of precipitation-hardenable alloys. We demonstrate how first-principles calculations of configurational and vibrational free energies can be used to predict precipitate phase boundaries of stable and metastable phases in Al-Cu alloys. Surprisingly, the formation entropy of a Cu impurity is found to be hugely positive (+2.7 kB/atom), leading to a dramatic enhancement in the solubility. The large entropy is dominated by the very low-frequency vibration of the small impurity atom (Cu) inside the large cage of the host (Al). The agreement between the GGA and experimental data is within 100 K for all phases, showing that accurate first-principles determination of metastable phase boundaries is now possible.
AB - Metastable precipitate phase boundaries are difficult to ascertain experimentally and yet are important for controlling the microstructure of precipitation-hardenable alloys. We demonstrate how first-principles calculations of configurational and vibrational free energies can be used to predict precipitate phase boundaries of stable and metastable phases in Al-Cu alloys. Surprisingly, the formation entropy of a Cu impurity is found to be hugely positive (+2.7 kB/atom), leading to a dramatic enhancement in the solubility. The large entropy is dominated by the very low-frequency vibration of the small impurity atom (Cu) inside the large cage of the host (Al). The agreement between the GGA and experimental data is within 100 K for all phases, showing that accurate first-principles determination of metastable phase boundaries is now possible.
UR - http://www.scopus.com/inward/record.url?scp=33644891622&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33644891622&partnerID=8YFLogxK
U2 - 10.1209/epl/i2005-10462-x
DO - 10.1209/epl/i2005-10462-x
M3 - Article
AN - SCOPUS:33644891622
VL - 73
SP - 719
EP - 725
JO - Journal de Physique (Paris), Lettres
JF - Journal de Physique (Paris), Lettres
SN - 0295-5075
IS - 5
ER -