High resolution detection of solute segregation to the cores of dislocations in grain boundaries
The segregation of solute atoms to grain boundaries in polycrystalline solids can be responsible for embrittlement of the boundaries. Auger electron spectroscopy and analytical electron microscopy (AEM) have verified the occurrence of solute segregation to grain boundaries, however, there has been little experimental evidence concerning the distribution of the solute within the plane of the interface. Au segregation causes a change in the primary dislocation structure of small angle (001) twist boundaries in Fe. (001) twist boundaries have been produced in bicrystals of both pure Fe, and Fe containing a small amount of Au. The boundary structure characteristic of pure Fe, which is square <110> dislocation network, changes to two different square dislocation networks, <110> and <100>-type, when 0.17 at% Au is added to the bicrystal and Au segregates to the boundary at its midplane. Rutherford backscattering spectroscopy was used to demonstrate that there was Au segregation to the interface, and analytical electron microscopy showed that the <100> network was Au-rich relative to the <110> network. The present study has clearly established that Au segregates extensively to the a<100> dislocation cores, it remains to understand why the presence of Au has a stronger influence on the core structure and energy of the a<100> rather than the a/2<111> dislocation, leading to the stabilization of the a<100> dislocation network. Theoretical calculations are needed to examine the influence of solute segregation on the core energy of dislocations in Fe and Fe alloys. Work is in progress to obtain quantitative information on the amount of Au at the cores.
- Research Organization:
- Homer Research Lab., Bethlehem Steel Corp., Bethlehem, PA (US); Dept. of Materials Science and Engineering, Cornell Univ., Ithaca, NY (US)
- OSTI ID:
- 6109968
- Journal Information:
- Scr. Metall.; (United States), Vol. 22:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
IRON
GRAIN BOUNDARIES
IRON BASE ALLOYS
ANNEALING
ATOMS
AUGER ELECTRON SPECTROSCOPY
DIFFUSION
DISLOCATIONS
GOLD ADDITIONS
INTERFACES
MICROSTRUCTURE
POLYCRYSTALS
SEGREGATION
SOLUTES
THEORETICAL DATA
ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTALS
DATA
ELECTRON SPECTROSCOPY
ELEMENTS
GOLD ALLOYS
HEAT TREATMENTS
INFORMATION
IRON ALLOYS
LINE DEFECTS
METALS
NUMERICAL DATA
SPECTROSCOPY
TRANSITION ELEMENTS
360102* - Metals & Alloys- Structure & Phase Studies