[Atomistic and elastic analyses of defects and small structures]. [Annual] progress report, [January 1, 1993--January 1, 1994]

Technical Report · Mon Aug 01 04:00:00 EDT 1994

DOI:https://doi.org/10.2172/10175485· OSTI ID:10175485

Focus was on interfacial segregation and its effect on interfacial phase stability. A method for performing atomisitc simulations in alloys was developed which accounts for equilibrium solute redistribution and allows determination of all thermodynamic properties. Segregation was shown to be strongly correlated with interfacial stresses on an atomic site-by-site basis and to greatly reduce the atomic level stresses, homogenizing the boundary. Differences in interfacial energies between elements plays a more important role than atomic size in predicting the dominant segregant. Effect of segregation on interfacial cohesive energies/ideal fracture toughness was examined in order to see how tight existing theoretical bounds on these quantities are. Small atomic cluster methods were used to determine average surface properties and to develop stereographic maps of surface energy, stress and segregation tendency for all surface orientations. Equilibrium Wulff plots (surface energy vs misorientation) for both elemental metal and binary alloys. Segregation significantly increases the order- disorder transformation temperatures at (001) surfaces in Ni-Pt and Cu-Pd alloys and steps on these surfaces resulted in transformation temperatures which were even higher near the steps. (Other alloys are covered, such as Ag-Cu, Ni-Cu, Ag-Au, Au-Pd).

• Research Organization: Michigan Univ., Ann Arbor, MI (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-88ER45367
• OSTI ID: 10175485
• Report Number(s): DOE/ER/45367--6; ON: DE94017047; BR: KC0201030
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102
BINARY ALLOY SYSTEMS
INTERFACES
ORDER-DISORDER TRANSFORMATIONS
PROGRESS REPORT
SEGREGATION
STRUCTURE AND PHASE STUDIES
SURFACE PROPERTIES
SURFACES
THERMODYNAMIC PROPERTIES