Concept Of Hardening Research Articles

Generation of Interstitial Atoms in FCC Single Crystals

A mathematical model of generation and accumulation of interstitial atoms in plastically deformable pure FCC metals is suggested based on the concept of hardening and recovery that links the phenomena proceeding in the deformable crystal material with the behavior of crystal structure defects. The model comprises kinetics equations for point defects – mono- and bivacancies and interstitial atoms – written with allowance for mechanisms of their generation and precipitation on sinks. Special attention is given to investigation of the influence of the velocity and character of motion of helical segments of expanding dislocation loops on generation of interstitial atoms. Concentrations of interstitial atoms generated in the process of plastic deformation are calculated.

Modeling of macroscopic strain localization in alloys with the L12 structure

Results of mathematical modeling of plastic strain superlocalization are presented with allowance for dislocation redistribution into dislocation walls. The model based on the concept of hardening and rest is used to construct equations describing kinetics of dislocations and substructure transformations. It is demonstrated that depending on the scenario of the strain model evolution in the microvolume of a deformable body, different types of localization are possible under the influence of stress concentrators.

Deformation mechanisms and the theory of structural superplasticity of metals

A new model of structural superplasticity is proposed on the basis of recent experimental data on the operative deformation mechanisms and the results of investigations of grain boundary properties. The concepts of hardening and recovery are used to analyse the superplastic nature, the development of these processes being associated with grain boundaries. According to the proposed model during superplastic flow the hardening due to easy generation of lattice dislocations (LD's) in the boundaries at the formation of grain boundary dislocation pile-ups is insignificant while the rate of the recovery whose kinetics is determined by LD absorption by boundaries is high. On the basis of these conceptions a system of equations of the dislocation kinetics is obtained which describes the experimental curve of superplastic deformation and the principal causes of a number of structural effects which have not been satisfactorily explained before are given. [Russian Text Ignored].