A model of non-equilibrium grain-boundary segregation of solute was expressed with graphs for the isothermal aging at various temperatures after quenching from a solution temperature. It was found from the graphical representations that when the samples were aged for a certain time at various temperatures there was a maximum value in the segregation concentration at a certain temperature. The aging time was equal or close to the critical time of non-equilibrium segregation corresponding to this temperature. This finding was experimentally confirmed with sulfur in a Ni-base superalloy with the aid of Auger electron spectroscopy. As an application of the new finding, a mechanism for intermediate temperature embrittlement of alloys was suggested and identified experimentally with tension tests of the superalloy.

Graphical Representation for Isothermal Kinetics of Non-Equilibrium Grain-Boundary Segregation. K.Wang, T.D.Xu, S.H.Song, C.Shao: Materials Characterization, 2011, 62[6], 575-81