Only a few experimental data are available in the literature for grain boundary expansion, primarily for isolated grain boundaries with a distinct orientation relation. From high-resolution transmission electron microscopy, values for Au of eGB=(0.04–0.10)×10-10m (Ref. [22]) or eGB=0.12×10-10m (Ref. [23]) are reported. From measurements of the grain boundary contact angle in an Al tricrystal, a value eGB=0.64×10-10m is reported by Shvindlerman et al. [24] applying a thermodynamic model. For nanocrystalline Pd [25] and Fe [26], values of eGB=0.23×10-10m and 0.19×10-10m were determined from density measurements and modeling of grain growth kinetics, respectively. A number of computer simulations of grain boundaries [27–30] deal with the issue of grain boundary expansion. Here, however, the choice of the interatomic potentials was found to have a substantial influence on the numerical results [27]. Most recently, grain boundary expansion data have been reported from molecular dynamics simulations on Ni, eGB=(0.28–0.42)×10-10m for random high-angle grain boundaries [30] and eGB=(0.39–0.41)×10-10m (at T = 1200 K) for Σ5 grain boundaries [29]. Here, the matching of the data values with the data of the dilatometric studies of Cu and Ni is remarkable.
molecular dynamics simulations on Ni
eGB
(0.28–0.42)×10-10m
m
molecular dynamics simulations on Ni
eGB
(0.39–0.41)×10-10m
m
molecular dynamics simulations on Ni
T
1200 K
K