Hydrogen segregation at grain boundaries in nanocrystalline nickel

Journal Article · Sat May 15 04:00:00 EDT 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90459-6· OSTI ID:6519983

Kirchheim, R ^[1]; Kownacka, I; Filipek, S M ^[2]

---

1. Max-Planck-Inst. fuer Metallforschung, Stuttgart (Germany)
2. Inst. of Physical Chemistry, Warsaw (Poland)

Nanocrystalline metals are polycrystalline metals with a grain size in the sub-micrometer range, and, therefore, the volume fraction of grain boundaries is large giving rise to an overall increase of solubility of impurities due to grain boundary segregation. The effect grain boundaries have on the behavior of hydrogen in nickel is somewhat controversial. Electrolytic doping of nickel samples with hydrogen is frequently used to initiate intergranular fracture, which is supposed to occur due to hydrogen segregation at grain boundaries. However, the effect of the boundaries on H-permeation appears to be negligible unless the grain size is 100 nm or less. Recent calculations of the H-segregation energy at a [Sigma] tilt boundary by Moody and Foiles using the embedded atom technique revealed a broad spectrum of energies ranging from 0.55 to 0.04 eV. These calculations and the measurements in nanocrystalline palladium /1/ are both evidence for a spectrum of segregation energies rather than a single value. In the present study the authors report on measurements of hydrogen solubility in nanocrystalline nickel at high pressures which they describe by assuming a Gaussian distribution of segregation energies in the grain boundaries. Thus values of the width of the distribution and its average energy are evaluated.

• OSTI ID: 6519983
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Journal Issue: 10 Vol. 28:10; ISSN SCRMEX; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
CRYSTAL STRUCTURE
CRYSTALS
DATA
DIFFUSION
ELECTRON MICROSCOPY
ELEMENTS
EXPERIMENTAL DATA
GRAIN BOUNDARIES
GRAIN SIZE
HYDROGEN
INFORMATION
METALS
MICROSCOPY
MICROSTRUCTURE
NICKEL
NONMETALS
NUMERICAL DATA
PERMEABILITY
POLYCRYSTALS
SEGREGATION
SIZE
SOLUBILITY
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY