Localization of plastic deformation and fracture in aluminum polycrystals

The effect of the grain size as a basic structural parameter on plastic strain macrolocalization has been studied for polycrystalline aluminum. The mathematical form of the above dependence has been verified. The limiting cases have been defined both for small- and coarse-grain ranges. The effect of sample dimension on the macrolocalization period has been considered.Исследовано влияние размера зерна как основного параметра структуры на макролокализацию пластической деформации в поликристаллическом алюминии. Выполнена проверка математической записи указанной зависимости. Определены предельные случаи для областей малых и больших размеров зерен. Рассмотрено влияние размера образца на период макролокализации

Plastic deformation of solids viewed as a self-excited wave process

A self-excited wave model of plastic flow in crystalline solids is proposed. Experimental data on plastic flow in single crystals and polycrystalline solids involving different mechanisms have been correlated. The main types of strain localization in the materials investigated have been established and correlated with the respective stages of plastic flow curves. The best observing conditions have been defined for the major types of autowaves emerging by plastic deformation. The synergetic concepts of self-organization are shown to apply to description of plastic deformation. Suggested is a self-excited wave model of plastic flow in materials with different mechanisms of deformation

Regular features of the evolutionary behaviour exhibited by plastic flow localisation and fracture in metals and alloys

Considered is the generation of self-excited waves by non-homogeneous plastic flow observed for a range of alloys in a single-crystal and a polycrystalline state at the stage of linear work hardening. It is found that under such conditions, in plastically deforming single austenitic crystals and polycrystalline Zr base alloys there originate self-excited waves propagating in the material volume at a rate of ~ 10-5 m/s. It turns out that the motion velocity of self-excited waves is inversely proportional to the extent of work hardening, which sets them apart from the well-known plasticity waves. The effect of extension axis orientation on the kinetic parameters of self-excited waves observable in the single crystals tested has been examined. Plastic flow is regarded as a self-organization process occurring in a deforming medium, and the universality of the proposed approach to the description of plastic flow is substantiated. The evolution of self-excited waves in the deforming alloys during material's transition to parabolic work hardening and on to fracture is described