Atomistic studies of grain boundaries with segregated impurities. Progress report, July 1, 1979-June 30, 1980

Technical Report · Sat Mar 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/5504868· OSTI ID:5504868

Vitek, V

The necessary precursor for any atomistic studies is a description of interatomic forces. Since no satisfactory description of interatomic forces in binary alloys could be found, the first stage of the research was devoted to this problem. The energy of the lattice was written as a sum of pair interactions and of a density dependent term. For pure metals the parameters in both the pair potential and the density dependent term were determined so as to fit the cohesive energy and elastic constants, and satisfy the condition of equilibrium for the experimentally known lattice parameter. The potentials and density dependent terms for pure metals were then used in constructing the corresponding description of interatomic interactions in alloys, using a modified method. The principle modifications are use of density dependent terms and fitting of the enthalpy of mixing. These procedures are described in detail. The grain boundary studies were started for the systems Cu-Ag, Cu-Bi and Au-Ag. However, since the density dependent part of the energy must now be taken into account explicitly a substantial modification of existing computer programs for grain boundary calculations is needed. This is at present in progress and thus only the directions of this work are reported. A limited effort was also devoted to the development of a theory of intergranular fracture in embrittled materials. The main purpose is to establish a relationship between the cohesive energy and the plastic work which would enable us to use the recently developed technique of measuring the local stress of fracture for direct studies of intergranular cohesion.

• Research Organization: Pennsylvania Univ., Philadelphia (USA). Dept. of Materials Science and Engineering
• DOE Contract Number: AC02-79ER10429
• OSTI ID: 5504868
• Report Number(s): DOE/ER/10429-T1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
BISMUTH ALLOYS
COPPER ALLOYS
CRYSTAL STRUCTURE
ELASTICITY
ENTHALPY
GOLD ALLOYS
GRAIN BOUNDARIES
IMPURITIES
MECHANICAL PROPERTIES
MICROSTRUCTURE
PHYSICAL PROPERTIES
SEGREGATION
SILVER ALLOYS
THERMODYNAMIC PROPERTIES