The article applies to a piece of research inspired by the new technology of plastic metal forming called the KOBO method, which uses the mechanical and structural effects of cyclic changes of deformation path. Its commercial usage in the field of large plastic deformations, especially for the production of extruded elements made of hardly deformable metal alloys, naturally generated a question about the optimal conditions for carrying out the process and the criteria for their establishment, i.e., constitutive description. In this context, the work provides data on the force and energy consumption of aluminum and 7075 aluminum alloy extrusion processes, carried out using the KOBO method, and their dependence on the strain rate and temperature. The mechanism of deformation occurring during extrusion by the KOBO method was identified as visco-plastic flow. Characteristic parameters of the process, such as viscosity coefficiency, activation energy, activated volume, and the concentration of point defects generated during the process were evaluated.

KOBO extrusion of metals and alloys strongly activates the point defect generation processes, as a result of which they reach a concentration exceeding the equilibrium level by many orders of magnitude. This leads to significant acceleration of diffusion phenomena which in heat-treatable alloys may cause disturbance of the thermodynamic equilibrium between the solid solution decomposition and dissolution of precipitates. In this work, measurements of mechanical and electrical properties and structural observations Cu1Cr0.1Zr alloy subjected to low-temperature KOBO extrusion at different stages of multi-variant heat treatment were conducted. In addition, the geometry of the extruded alloy’s flow zone was analyzed and the obtained results made it possible to assess the effectiveness of experimental procedures, including product formation with high extrusion ratio λ, aimed at achieving of high and thermally stable functional properties of the material.

Materials were obtained from commercial zirconium powders. 1 mass%, 2.5 mass% and 16 mass% of niobium powders were used as the reinforcing phase. The SPS method and the extrusion method classified as the SPD method were used. Relative density materials of up to 98% were obtained. The microstructure of the sintered Zr-xNb materials differs from that of the extruded materials. Due to the flammability of zirconium powders, no mechanical alloying was used; only mixing of zirconium and niobium powders in water and isopropyl alcohol. Niobium was grouped in clusters with an average niobium particle size of about 10 μm up to 20 μm. According to the Zr-Nb phase equilibrium system, the stable phase at RT was the hexagonal α-phase. The tests were carried out for materials without the additional annealing process. The effect of niobium as a β-Zr phase stabilizer is confirmed by XRD. Materials differed in their phase composition, and for both methods the β-Zr phase was present in obtained materials. A very favorable effect of niobium on the increase in corrosion resistance was observed, compared to the material obtained from the powder without the addition of niobium.