Model Of Grain Boundary Segregation Research Articles

Non-equilibrium grain-boundary segregation kinetics

A new model is proposed in this article concerning non-equilibrium grain-boundary segregation kinetics. The model not only includes the isothermal non-equilibrium grain-boundary segregation kinetics but also provides a formula for calculating the non-equilibrium segregation level under continuous cooling. Results calculated from the non-equilibrium grain-boundary segregation model for boron in steel grade Type 316 and chromium in steel grade $$2\tfrac{1}{4}$$ % Cr-1 % Mo are in satisfactory agreement with the observed data for experimental measurements.

Grain boundary segregation of carbon in iron

The distribution of C14 in a series of a-phase Fe-C alloys was studied autoradiographically. Excess carbon was present near grain boundaries in specimens equilibrated at 500‡ and 600‡C; the amount of carbon near the grain boundaries was found to decrease as the equilibration temperature increased. Electron microscopy of the specimens subsequent to the autoradiography showed that no grain boundary precipitates were present. The results are compared with the theories of nonequilibrium vacancy-aided segregation and Gibbsian adsorption, and also with McLean's model of grain boundary segregation. It is shown that the technique measures directly the quantity of thermodynamic interest, the total excess solute per unit area of grain boundary.