Three dimensional models of the plasticity of metal crystals have been developed. Microscopic and macroscopic properties were considered.
The models were compared to experimental investigations of recovery in aluminium alloys. The work proved the applicability of the simulation to a typical N-body problem; the cross slip was sufficient to simulate the logarithmic decrease in mechanical properties observed.
The models were used to investigate dynamic strain ageing associated with dynamic interaction of dislocations with mobile solutes. Good agreement with experiment was achieved. The mechanism of dislocation patterning and strain localization during plastic flow was also investigated. An instability which propagated at constant velocity was evident in the model.
To contribute data for comparison with the models, an electron microscopy study of slip band growth and fine structure in monocrystal and polycrystal copper-aluminium alloys was undertaken. The propagation of dislocations due to imposed stresses was observed.
The proposed research has two aims:(i) investigate the self-organization of dislocations in crystalline solids during plastic flow,(ii) establish a connection between this microstructural organization and mechanical properties at macroscopic scale. It is based on a 3d simulation of dislocation motion and interaction in a dicrete lattice, which is being developed. The results obtained will be synthetized and will serve as a basis for further modelization of the evolution with time and space of dislocation populations during straining and for constructing constitutive equations. Comparison with available data and with experiment will essentially deal with:(i) the length scales of the microstructure, (ii) slip propagation and localization, (iii) testing the constitutive equations through their predictive ability in the domain of polycrystalline textures.
Funding SchemeCSC - Cost-sharing contracts