ABSTRACT
This chapter focuses on the new concepts of the strengthening of nanocrystals based on the competition of different plastic deformation mechanisms: dislocation slip and grain boundary gliding. It is well-known that the value of the theoretical (limiting) strength of the solid can be determined in fractions of the shear modulus. On the other hand, the most important element of the structure of nanocrystalline materials, which determines their strength properties, are the grain boundaries. The low-temperature grain boundary sliding (LGBS) mechanism is more efficiently realised, as is well-known, in nanocrystals produced by controlled annealing of the amorphous state. This is associated with the formation in late stages of crystallisation of thin grain boundary amorphous interlayers with higher thermal stability. Similar interlayers can be regarded as 'blurred' grain boundaries.
