Long-range segregation

The above treatment assumes that solute mixing in the liquid is the result of diffusion only. It can be modified to allow for partial or complete mixing in the liquid (see Chalmers In these circumstances long-range segregation will still occm. 

In the absence of constitutional supercooling, the behaviour dining growth is essentially the same as that of pure materials with the exception that long-range segregational effects occur which are associated with the initid and final transients in the solidification process (Fig. 4.13). 

Long-range segregation can result either from changes that occur in the liquid before the solidification front has proceeded very far or as the result of fluid motion in the mushy zone behind the solidification front. 

Figure 6.4 shows that long-range diff usivities of water in Nafion membranes measured by QENS, Di are equal to self-diff usivities determined by PFG-NMR, Dg, at A > 10. In well-hydrated membranes, the major geometric constraints for water mobility due to the phase-segregated, random network morphology of... 

Jalava PI, Salonen RO, Halinen AI, Penttinen P, Pennanen AS, Sillanpaa M, Sandell E, Hillamo R, Hirvonen M-R (2006) In vitro inflammatory and cytotoxic effects of size-segregated particulate samples collected during long-range transport of wildfire smoke to Helsinki. Toxicol Appl Pharmacol 215 341-353... 

A very important characteristic of the subsurface region is the surface concentration of the atoms. For alloys, it is customary to speak of the surface segregation of the component whose surface concentration exceeds the bulk one. With an increase in the distance from the surface, the local concentrations of the particles tend to their bulk values. This also relates to the other characteristics of particle distribution determining short- and long-range orders, which in the subsurface region can have a great anisotropy. 

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