Ab-initio modeling of metastable precipitation processes in aluminum 7xxx alloys

作者：de Jong Maarten^*; van der Zwaag Sybrand; Sluiter Marcel

来源：International Journal of Materials Research, 2012, 103(8): 972-979.

DOI：10.3139/146.110807

• Precipitation energetics
• Ab-initio modeling
• Aluminum alloys
• Thermodynamics
• Alloy design

Aluminum 7000-alloys depend primarily on precipitation hardening for their strength. Precipitate phases may form through complex precipitation sequences, in which a precipitate gradually evolves towards a thermodynamically stable state via intermediate thermodynamically metastable phases. During the precipitation sequence, precipitates may change not only size but also shape, composition and coherence with the matrix. Despite the industrial significance of aluminum-7000 alloys, the precipitation process remains poorly understood, as evinced by a large amount of scatter in the experimentally observed data on precipitation. In this work, we employ density functional theory first principles calculations to study the energetics of precipitation. It is shown that for the various precipitate families, a monotonic decrease in bulk formation enthalpy occurs during the precipitation sequence and various proposed structures are discarded based on unreasonable energetics. Further, the influences of strain and interfacial energy are quantified and a structural sequence is proposed for the important eta precipitate family based on energetics.

• 出版日期2012-8