Determination of grain boundary volume expansion by HREM

Abstract

The submllled manuscrlpl hall been authored[ by a conlraclor of the U.S. Government| under contract No. W-31-109-ENG-38.| Accordingly,the U.S. Governmentrellllns a| nonexcluslve,royally-free license to publish| or reproduce the published form of thls| contribution, or allow others to do so, for| u.s. eovemme,pu_. l DISCLMMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Grain boundary excess volume and defect annealing of copper after high-pressure torsion

“…[22]) or $e_{\mathit{GB}}=0.12\times {10}^{-10}\text{m}$ (Ref. [23]) are reported. From measurements of the grain boundary contact angle in an Al tricrystal, a value $e_{\mathit{GB}}=0.64\times {10}^{-10}\text{m}$ is reported by Shvindlerman et al [24] applying a thermodynamic model.…”

The effect of three‐fold astigmatism on measurements of grain boundary volume expansion by high‐resolution transmission electron microscopy

“…The lattice fringe displacement method was originally developed by Stobbs and co‐workers, who realized that, by determining the intensity profiles of fringes from lattice planes parallel to an interface and extrapolating via regression analysis from regions far away from the boundary, the rigid‐body translation normal to the interface could be derived with considerable precision (Stobbs et al ., 1984; Wood et al ., 1984). Since only very special GBs could be analysed in this manner, the method was modified to allow displacement measurements for more general, including asymmetric, tilt GBs (Merkle, 1992; Buckett & Merkle, 1994). Briefly, the technique relies on the presence of a characteristic peak‐like motif in the HREM contrast that can be associated with the locus of an atomic column.…”

“…After taking into account the number of atomic columns in the core region (those between the dashed lines) per GB unit cell, the volume expansion δ is determined from the difference between measured width W and the unrelaxed width W u , i.e. δ = W − W u (Buckett & Merkle, 1994).…”

Origin of differences in the excess volume of copper and nickel grain boundaries

“…While excess volume is recognized as a key materials parameter probing it in real materials remains extremely challenging. A small number of studies have characterized excess volume for specific GBs using high-resolution electron microscopy [12,13]. More recently ensemble average excess volumes have been determined for bulk polycrystalline samples of copper and nickel using highprecision difference dilatometry [14,15].…”