Atomistic studies of grain boundaries in alloys and compounds

Technical Report · Wed May 02 04:00:00 UTC 1990

DOI:https://doi.org/10.2172/6902715· OSTI ID:6902715

Vitek, V

The main goal of this research project has been to investigate theoretically the atomic structure of gain boundaries in binary alloys, both discovered and ordered, and contribute thus to our understanding of atomic level processes affecting mechanical properties of polycrystalline materials. In particular, we concentrate on those structural features which distinguish boundaries in alloys from those in pure metals and might be responsible for remarkable differences in their fracture behavior. Atomistic computer modeling of grain boundaries is the principal technique employed in this project. However, such calculations are only meaningful if adequate descriptions of interatomic forces are available. For pure elements a wide variety of such descriptions have been developed in recent years but much less has been done for alloys. For this reason a large component of this research has been the development of such descriptions and two different approaches have been pursued. In this report we first summarize constructions of N-body potentials for alloys and describe briefly the present status of the development of the LMTO based tight-binding technique. Studies of grain boundaries, summarized in this report, concentrated on two problems: segregation to grain boundaries in the copper-bismuth system and boundaries in L1{sub 2} compounds. In the former case the structural changes induced by segregation as well as conditions for saturation and faceting of the boundaries were investigated. In the latter case we focused on the relationship between the strength of ordering and the boundary structure. Significant differences which may be responsible for distinct fracture properties of pure metals, weakly ordered and strongly ordered compounds, have been found.

• Research Organization: Pennsylvania Univ., Philadelphia, PA (USA). Board of Trustees
• Sponsoring Organization: DOE/ER
• DOE Contract Number: FG02-87ER45295
• OSTI ID: 6902715
• Report Number(s): DOE/ER/45295-3; ON: DE90012401
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
BISMUTH ALLOYS
COPPER ALLOYS
CRYSTAL STRUCTURE
DOCUMENT TYPES
GRAIN BOUNDARIES
IMPURITIES
INTERMETALLIC COMPOUNDS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
PHASE STUDIES
PROGRESS REPORT
TEMPERATURE DEPENDENCE