Grain boundary segregations in nanocrystalline alloys

The dependence of grain boundary segregations and alloy composition in the bulk of the grain on the grain size was considered. At moderate temperatures, there is a critical grain size for which the integrated degree of alloy decomposition reaches its maximum; this size increases as the average (over the sample) impurity concentration decreases. In complex alloys, the type of the component that segregates on the boundaries depends on the grain size. For segregation kinetics, an approximate analytical solution was obtained based on the assumption that the grain boundary is an ideal drain for the impurity. The equilibrium grain size exists below the critical temperature and its temperature dependence is nonmonotonic in the general case. A segregation mechanism of stabilization of nonequilibrium grain boundaries in nanocrystalline alloys obtained by severe plastic deformation was suggested.