Misorientation dependence of the grain boundary migration rate: role of elastic anisotropy

Abstract

In this work, numerical computations of image forces and stored energy during the growth of a strain free grain within a recovered matrix containing an array of identical dislocations are performed. A decrease of the stored energy is observed when image forces are attractive and an increase when image forces are repulsive. The variation of elastic energy depends closely on the material elastic anisotropy, the number of dislocations in the array and its initial distance to grain boundary. For an array of 20 edge dislocations and the motion of a planar grain boundary over approximately 180 atomic spacing, the magnitude of the energy variation is on the order of one dislocation line energy for Al and six for Cu, which is significant in both cases. Furthermore, by sweeping the whole orientation space for FCC crystals, it is shown that grain boundaries near a 111 40˚misorientation are among those that can display the highest attractive forces on edge dislocations. Since grain boundary migration is driven by the reduction of stored energy, the results are analyzed in light of experimental recrystallization data in FCC metals which show that the fastest moving boundaries are often characterized by misorientation axis around 111 and misorientation angle close to 40˚.

Energy variation and stress fields of spherical inclusions with eigenstrain in three-dimensional anisotropic bi-materials

“…Hence, the elastic strain energy can increase or decrease and thus can either promote or hinder interface motion. The significance of such an image effect on interface motion was previously studied for distributions of dislocations (Richeton et al, 2020), providing insights into the connection between interface motion and crystallographic disorientations.…”

Elastic anisotropy and its temperature dependence for cubic crystals revealed by molecular dynamics simulations

“…Among them, the elastic constants are the fundamental mechanical property parameters that characterize the elastic deformation behavior of materials, while their anisotropy reflects the difference in the resistance to elastic deformation along different crystalline directions. A large volume of studies have been devoted to explore the influences of elastic anisotropy on dislocation motion [1][2][3], grain boundary migration [4,5], crack initiation [6], phase transformation [7], etc. For instance, it was reported that the anisotropic elastic interaction played a decisive role in determining the evolution of dislocations and solid-solid interfaces by affecting the dislocation stress fields [1,3,6] and/or the interface energy [4,5,7] under different service conditions.…”

“…A large volume of studies have been devoted to explore the influences of elastic anisotropy on dislocation motion [1][2][3], grain boundary migration [4,5], crack initiation [6], phase transformation [7], etc. For instance, it was reported that the anisotropic elastic interaction played a decisive role in determining the evolution of dislocations and solid-solid interfaces by affecting the dislocation stress fields [1,3,6] and/or the interface energy [4,5,7] under different service conditions. Meanwhile, many studies have also been carried out to reveal the influences of different environmental conditions on the elastic anisotropy.…”

Surface effects on image stresses and dislocation pile-ups in anisotropic bi-crystals

“…Therefore, the consideration of these complex interactions is important to optimize materials microstructure and their components geometry and size. As typical examples, we can cite the grain size dependence on the yield stress through the Hall-Petch's relationship (Hall, 1951;Petch, 1953;Armstrong, 1970), the strengthening due to grain boundaries (Lim et al, 2016) and twin boundaries (Schneider et al, 2020), the driving force for GB migration (Richeton et al, 2020), interfacial shearing (Chu et al, 2013;Ovid'ko and Sheinerman, 2017), grain rotation (Borodin et al, 2017), slip/twin transmission (Xiao et al, 2017;Lin et al, 2018;Haouala et al, 2020) or the micro-beam size effect due to dislocation starvation at free surfaces (Gao et al, 2010). Indeed, the grain size effect in polycrystalline specimen is usually explained by the stress concentration at the tip of slip bands terminating at GB using dislocation pile-up model (Eshelby et al, 1951;Armstrong, 2014;Cordero et al, 2016).…”