Grain boundary phase equilibria in metallic systems: Progress report, December 1, 1986--April 30, 1989

Technical Report · Sat Apr 01 00:00:00 EST 1989

DOI:https://doi.org/10.2172/6295548· OSTI ID:6295548

Deymier, P. A.

A method for growing high purity aluminum bicrystals with controlled misorientation and grain boundary (GB) plane inclination has been successfully implemented. Computer simulations of a ..sigma.. = 5 (001) symmetric tilt GB in aluminum does not undergo premelting but exhibit a second-order transition associated with an increase in atomic mobility in the GB plane. A GB rotation transition in a ..sigma.. = 5 bicrystal from a (210) inclination to a (38 19 1) orientation has been characterized as a first order phase transition. It takes place by differential shear of the grains across the interface. The driving force for rotation is related to the amount of torque the interface may sustain. The elastic energy contribution to segregation of point defects to planar defects is short range. This elastic contribution is long range if the GB is stresses with points of dilatation. Segregation may result in the complete filling of the interface with solute atoms or the formation of regions of high solute concentration along the interface. High resolution electron microscopy images of a near twin boundary in aluminum shows relaxation of secondary grain boundary dislocation cores when the burgers vectors are parallel to the interface plane. The relaxation leads to a local change in translation state of the GB. 8 figs.

• Research Organization: Univ. of Arizona, Tucson, AZ (United States)
• DOE Contract Number: FG02-87ER45285
• OSTI ID: 6295548
• Report Number(s): DOE/ER/45285-3; ON: DE89011787
• Resource Relation: Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
FABRICATION
BICRYSTALS
COMPUTERIZED SIMULATION
EQUILIBRIUM
GRAIN BOUNDARIES
GRAIN ORIENTATION
INTERFACES
MICROSTRUCTURE
PHASE TRANSFORMATIONS
PROGRESS REPORT
SEGREGATION
TEMPERATURE DEPENDENCE
TORQUE
TWINNING
CRYSTAL STRUCTURE
CRYSTALS
DOCUMENT TYPES
ELEMENTS
METALS
ORIENTATION
POLYCRYSTALS
SIMULATION
360101* - Metals & Alloys- Preparation & Fabrication
360102 - Metals & Alloys- Structure & Phase Studies