Conclusion
The real grain boundary - Effects of temperature and chemistry

Real materials are sometimes subjected to changes in ambient temperature, and are rarely used in their purest form. More often than not, they contain elements in solution, either in the form of solutes, added deliberately to improve one of their properties, or in the form of impurities that cannot be eliminated by their manufacturing methods. It is therefore necessary to understand the effects of temperature and chemistry on grain boundaries in order to understand, or even control, the behavior of a polycrystalline assembly.

Thus, structural transformations occurring at temperature can lead to the formation of a more brittle or corrodible phase at the joint than the matrix, or to the appearance of a quasi-amorphous film that has a significant influence on intergranular sliding. Similarly, modifications to the intergranular structure under the effect of a solute...