Thermodynamic and structural properties of (001) twist boundaries in gold

Journal Article · Wed May 01 04:00:00 EDT 1991 · Journal of Materials Research; (USA)

DOI:https://doi.org/10.1557/JMR.1991.0999· OSTI ID:5692292

Najafabadi, R; Srolovitz, D J ^[1]; LeSar, R ^[2]

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1. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (USA)
2. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)

We have employed the Local Harmonic (LH) model and the Embedded Atom Method (EAM) to examine the structural and thermodynamic properties of a series of twelve (001) twist boundaries in gold for temperatures between 0 K and 700 K. For the majority of the grain boundary misorientations, metastable structures were observed with grain boundary energies that were typically less than 0.1% larger than the stable structures. Four of the twelve grain boundaries underwent first order structural phase transitions as seen by the crossing of the free energy versus temperature curves for the competing structures. Relatively small cusps or inflections in the grain boundary free energy versus misorientation curves were observed at {Sigma}5 (36.87{degree}) and {Sigma}13 (22.62{degree}) at low temperatures, at {Sigma}13 (22.62{degree}) and {Sigma}17 (28.07{degree}) at intermediate temperatures, and at {Sigma}5 (36.87{degree}) and {Sigma}17 (28.07{degree}) at elevated temperatures. A maximum in the grain boundary entropy versus misorientation was observed at {Sigma}17 (28.07{degree}) for all temperatures, and local minima were observed at {Sigma}5 (36.87{degree}) at low temperature and in {Sigma}13 (22.62{degree}) at high temperature. The excess volume associated with the grain boundary shows a roughly linear dependence on grain boundary free energy at each temperature examined. The room-temperature mean-square vibrational amplitude is approximately 25% larger than that for the bulk at the (002) plane adjacent to the boundary and decays to within 2% of the bulk value by the second (002) plane from the boundary. The room-temperature mean-square vibrational amplitude is dominated by the in-plane (parallel to the grain boundary) vibrations at the (002) plane nearest the grain boundary.

• DOE Contract Number: FG02-88ER45367
• OSTI ID: 5692292
• Journal Information: Journal of Materials Research; (USA), Journal Name: Journal of Materials Research; (USA) Vol. 6:5; ISSN JMREE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360104* -- Metals & Alloys-- Physical Properties
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
ELEMENTS
ENERGY
ENTROPY
FREE ENERGY
GOLD
GRAIN BOUNDARIES
HARMONIC OSCILLATOR MODELS
HIGH TEMPERATURE
LOW TEMPERATURE
MATHEMATICAL MODELS
MEDIUM TEMPERATURE
METALS
MICROSTRUCTURE
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE