Thermally activated grain boundary unpinning

Suppression of grain growth in nanocrystalline Bi2Te3 through oxide particle dispersions

“…The continued grain growth at higher temperatures could be due to thermal activation of boundary unpinning. This process is suggested by Gore et al 17 to become important for very small pinning particle sizes and high temperatures. The authors evaluated the tendency for thermally activated unpinning in an Fe alloy, and suggested that thermally activated unpinning could play a role below a particle diameter of about D ¼ 50 nm, which is on the order of the particle sizes in this study.…”

“…16 The classical Zener relation dictates that the most effective pinning will come from the smallest particles, however, when their size is reduced appreciably into the nc regime, other annealing-related microstructural phenomena can come into play. For example, below a certain critical particle diameter-on the order of 50 nm-thermally activated grain boundary unpinning can become prevalent, 17 while if the particles are sufficiently mobile, they can be dragged along by the boundary via diffusive mechanisms. 18 Under certain conditions, inclusions can also promote abnormal grain growth.…”

Evolution of Lath Substructure and Internal Stresses in a 9% Cr Steel during Creep

“…The processes of thermally activated unpinning have been found to become significant at small particle size and high temperatures. 46) However, the internal stress raised by dislocations with like signs and non-equilibrium lath boundaries should affect the dislocation motion irrespective of thermal activation. These stresses should provide an upper limit to the threshold stress.…”

Disabling of Nanoparticle Effects at Increased Temperature in Nanocomposite Solders

“…Atoms jump over the energy barrier, Q, with an attempt frequency, m (approximated by the Debye frequency for Sn; see Ref. 22 for other estimates), and with the probability of a successful jump given by Boltzmann statistics. Hence, the number of completed jumps, N, in time t c is given by…”