The paper proposes a model of strain resistance of alloy under high-temperature deformation. The model describes hardening of alloy due to the increase of dislocation density, as well as the barrier effect of blocking free dislocations, boundaries of grains and subgrains by dispersoids. The model also takes into account the softening processes associated with the recovery and dynamic recrystallization. The model has been tested on the rheological behavior of an Al-Mg alloy named AMg6 at temperatures of 400 and 500 ºC in the range of strain rates from 5 to 25 s -1 . It was found in this temperature -strain rate range that the curve of strain resistance of the AMg6 alloy consists of several portions. First there is hardening of the material, then there is material softening, which is again replaced by hardening of the material. With the use of the electron backscatter diffraction technique and transmission electron microscopy, it was found that the main process of softening at investigated temperatures is dynamic recrystallization. The appearance of the second portion of hardening on the strain resistance curve is the inhibition of dynamic recrystallization, as well as manifestation of the barrier effect of blocking free dislocations, grain and subgrain boundaries by dispersoids.

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Adhering to the structural-phenomenological approach, we develop a computational model of aluminum matrix composite deformation. The model allows us to simulate the stress-strain state parameters of the composite at the microscopic and macroscopic scales and in different loading scenarios. The composite is produced by sintering, and it has a cellular internal structure. The SiC reinforcing particles are grouped around sintered aluminum alloy pellets, forming a stratum. It has been experimentally established that, during the hot deformation process, the stratum undergoes structural changes. The changes influence the effective mechanical properties of the stratum. In order to account for these changes, we use the rule of mixtures, assuming the plastic flow properties of the stratum to be distributed proportionally to the volume fraction of its constituents. The model is used to simulate stress-strain state evolution at the microscopic and macroscopic scales in three loading scenarios -tension, compression and shear. We construct equivalent (von Mises) strain and average normal stress distribution fields in the finite-element nodes of the finite element mesh of a randomly selected micro volume and show that the local plastic deformation regions emerge in the composite structure. The presence of tensile stresses is also noted, which are the most adverse in terms of internal fracture probability.