Mechanism of Solid Solution Hardening: Quasilocalisation of Dislocation Kinks

Abstract

The sensitivity of the mechanical properties of materials to violations of the translational invariance of the crystal lattice makes it possible to manipulate these properties in the desired direction by doping or creating solid solutions. The paper theoretically studies the mechanisms of such manipulation in relation to materials in which the mobility of dislocations is controlled mainly by the potential relief of the crystal lattice – the so-called Peierls relief. Due to the concentration of alloying atoms in dislocation nuclei, which play the role of traps for these atoms, the dynamic properties of dislocations change, which also leads to modification of the macroscopic mechanical properties of the material. The theory of the effect of doping on the kink mechanism of overcoming the Peierls barriers is constructed taking into account the disordered content of solution atoms in dislocation nuclei. Correspondingly, the direct description of the kinetics of elementary processes characteristic of kinks has been replaced by a statistical description. The multidirectional effect of fluctuations in the solutes distribution, which increase the rate of formation of pairs of kinks, but inhibit the propagation of kinks along dislocation lines, is considered. Inhibition of kinks can lead to an anomalous nature of their mobility, so-called quasilocalisation. The conditions for the predominance of the accelerating or inhibiting factor corresponding in macroscopic terms to the hardening or softening of the material are found.