Influence of the Peierls relief on size effects in plastic deformation of micro- and nanocrystals of body-centered cubic metals

The influence of the Peierls relief and Peierls stresses on the size effects in micro- and nanocrystals of metals with a body-centered cubic (bcc) lattice has been theoretically discussed in the framework of the dislocation-kinetic approach. It has been found that, as compared to micro- and nanocrystals with a facecentered cubic (fcc) lattice, for the bcc crystals, the exponent n in the power law σ ～ D ^?n (where σ is the flow stress and D is the transverse size of the crystal) is the smaller, the higher is the critical temperature T _c above which the Peierls relief ceases to control the motion of dislocations in the bcc metals. The specific features of the influence of the Peierls relief on the coefficient of strain-rate sensitivity of the flow stresses in microcrystals of the bcc lattice have also been discussed. The theoretical results have been illustrated by the experimental data available in the literature.