The ''solidification'' of grain boundaries with increasing temperature

The aim of the paper is to explain the recently observed de-wetting grain boundary transition with increasing temperature. On the example of a bicrystal from the Fe-6at.%Si alloy, it was found recently that as temperature is increased, the following GB transitions take place: ''solid'' (or regular) GB → ''premelted'' GB → ''solid'' GB. At the same time the wetting/de-wetting transitions have taken place. Another example of such GB behavior wa discovered during sintering of alumina. The inverse melting behavior is explained as follows: low melting point impurities cause GB premelting at low temperatures. However de-segregation of impurities at high temperatures causes return of the GB structure to its regular ''solid'' state