Solute segregation transition and drag force on grain boundaries

Segregation and wetting transition at dislocations

“…For segregation at dislocations considered in this study, we followt he segregation model developed recently for grain boundary [20] in ab inary substitutional alloy to accountfor the solute-dislocation and solute-solute interactions. In this approach, the chemical potential of solute atoms in ac hemically homogeneousb ut structurally nonuniform (incoherent or defective) system is expressed as…”

“…We assumet hat the chemical free energy of the alloy can be approximated by ar egular solution model with nearest neighbor interactions. Then according to Ma et al [20] D…”

“…[10,11,12] Hillert [11,12] pioneeredt he use of ar egular solution model in nonuniform systems, which was later applied extensivelyt ot reat solute segregation at surfaces and interfaces. [13][14][15][16][17][18][19] In this article, we use the continuum modeldevelopedbyMa et al [20] forgrain boundary segregation based on gradient thermodynamics and the phase field modelo fd islocations developed by Wang et al [21,22] and Shen et al [23,24] to investigate solute segregation and wetting transition at dislocations and the corresponding drag forceo nd islocation glide.…”

“…Conversely, if the level of segregation is high, large concentration gradientse xist near the defects and their contributions to the chemical potential (including coherency strain energy) mustbei ncludedi nt he condition for equilibrium. In arecent studyonimpuritysegregation at grain boundaries, [20] it was shown that the consideration of solute-soluteinteractions results in afirst-order segregation transition at grain boundaries, leading to as harpt ransition of grain boundarym obility as af unction of temperature. Similar effects are expected for impurity segregation at other defects and haveb een demonstrated for solutedislocation interactions.…”

Microstructural Evolution Based on Fundamental Interfacial Properties

“…We investigated solute segregation at grain boundaries and the corresponding drag effect on grain boundary migration. A continuum model of grain boundary segregation based on kinetic Monte Carlo (Mendelev and Srolovitz 2001a, 2001b, 2001d, 2002b, 2002c, gradient thermodynamics and its discrete counterpart (discrete lattice model) have been developed (Ma, Dregia et al 2003) and analytical theory Srolovitz 2000, 2001b). The models variously include heat of segregation, intrinsic boundary mobility, solute diffusivity, co-segregation, solute thermodynamics, concentration gradients, spatial variation of gradientenergy coefficients, and the spatial variation of atomic volume and concentration dependence of solute -grain boundary interactions.…”