Determination of Percolation Threshold for Random Boundary Network on the Basis of EBSD/OIM Observations |
| Journal |
Materials Science Forum (Volumes 539 - 543) |
| Volume |
THERMEC 2006 |
| Edited by |
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran |
| Pages |
2371-2376 |
| DOI |
10.4028/www.scientific.net/MSF.539-543.2371 |
| Online since |
March, 2007 |
| Authors |
Sadahiro Tsurekawa, Shinya Nakamichi, Tadao Watanabe |
| Keywords |
Connectivity, Electron Backscatter Diffraction (EBSD), Grain Boundary, Grain Boundary Character Distribution (GBCD), Intergrangular Corrosion, Percolation |
| Abstract |
Grain boundary engineering through the control of grain boundary character distribution
(GBCD) has been extensively employed as a powerful tool for achieving enhanced properties and for
development of high performance both structural and functional polycrystalline materials. Many
efforts were made firstly to increase the frequency of low-energy CSL boundaries of polycrystalline
materials in grain boundary engineering. However, the connectivity of grain boundaries can be an
important microstructural parameter governing bulk properties of polycrystalline materials as well as
the GBCD. In the present work, the connectivity of random grain boundaries was quantitatively
evaluated using both the triple junction distribution and random boundary cluster length on the basis
of SEM-EBSD/OIM observations, and then these evaluated parameters were linked to intergranular
corrosion of SUS304 stainless steel. We have found that the length of the maximum random
boundary cluster drastically decrease with increasing CSL boundaries in the fraction ranging 60 –
80% CSL boundaries, which leads to percolation threshold occurring at approximately 70±5% CSL
boundary fraction (at 30±5% random boundary fraction). The experimentally observed percolation
threshold is much higher than theoretically obtained one based on randomly assembled network (at
35% resistant bonds for a 2D hexagonal lattice). In addition, the fraction of resistant triple junctions is
found to increase with increasing the the CSL boundary fraction. An increase in the frequency of
resistant triple junctions can enhance intergranular corrosion resistance of polycrystalline austenitic
stainless steel even if the GBCD is the same. |
| Full Paper |
Get the full paper by clicking here
|
