Cu/Mg-composite rods, inside the Cu-shells of which 1 or 400 Mg-filaments are contained, were obtained by hydmextrusion at room temperature. The structure, microhardness and electrical properties of the obtained composites have been studied both in the as-extruded state and after various heat treatments. It is shown, at heating to 450 degrees C, that the solid-state reactions between copper and magnesium lead to the formation of the porous Mg-based solid solution and two sub-layers of CuMg2 and Cu2Mg intermetallic phases (thick and thin, respectively) at the interface. As a result of heating to 530 degrees C, high-strength filaments based on these intermetallic phases are formed in the composites. Annealing at 750 degrees C completely changes the structure of Cu/Mg-composites. Instead of 400 Mg-filaments, one core is formed, which has an eutectic structure and consists of Cu-based fcc-solid solution with islands of Cu2Mg-phase. It was found that, as a result of these reactions, the microhardness of filaments increases by more than an order of magnitude, while the electrical resistivity of the composite remains almost unchanged. The subsequent deformation further increases the strength of Cu/Mg-composites. A conclusion is made that the method for obtaining high-strength Cu/Mg-composite wires tested in this work is new and promising.

The structure and the mechanical and electrical properties of composites with 7 and 49 magnesium fibers in the copper matrix are studied in this work. It was found that the strength of a deformed composite wire with the maximum volume fraction of Cu/Mg interfaces exceeds the theoretical estimate and the strength of pure copper. It is shown that deformation-induced formation of high-strength solid solutions of magnesium in copper at the interfaces of the composites occurs during the manufacturing process. The low electrical resistivity of the composites is provided by a copper shell.

The copper-based alloys with high strength and low electrical resistivity are of interest for many practical applications. In this study, Cu / Mg-composites with 1, 7 and 49 magnesium filaments in Cu-matrix have been obtained by hyrdoextrusion at room temperature. The structure, mechanical and electrical properties of the composite rods and thin wires in the deformed and annealed states have been investigated. The strength of the deformed Cu / Mg-composite with a minimal volume fraction of magnesium was found to be abnormally high. The increase of magnesium microhardness was revealed to be near the interface. A change in the lattice constant of the Cu-matrix in the deformed Cu / Mg-composites is discovered by the XRD-method. It has been concluded that, under severe plastic deformation, different solid solutions form on the Cu / Mg-interfaces due to mechanical alloying processes. The Cu / Mg-composite with a maximal volume fraction of Mg has the lowest strength in the deformed state, however, it becomes the strongest one after annealing at 200°C due to annealing hardening of magnesium. The temperature dependences of the electrical resistivity of Cu / Mg-composites differ significantly from each other. During heating, three eutectic transformations are realized in the composite with 7 Mg-filaments. As a result, the electrical resistivity of the deformed Cu / 7Mg-composite increases almost two times. The specific electrical resistivity of the composite with 49 Mg-filaments is a bit different from the electrical resistivity of deformed copper. The mechanisms of structure formation during the heating of these composites have been shown to be significantly different. The obtained results can be used for the development of high-strength Cu-based conductors.

Cu/Mg-composites, the copper matrix of which contains 1, 7 and 2730 magnesium filaments, were obtained by hyrdoextrusion at room temperature. The structure, mechanical and electrical properties of the deformed composite rods and thin wires were investigated. The yield strength and electrical resistivity were theoretically calculated and these estimations were compared with the experimental results. The XRD-method allowed discovering a change of the lattice constant of the Cu-matrix under deformation of the composites. It has been concluded that, under severe plastic deformation, a supersaturated Cu-based solid solution forms on the Cu/Mg-interface. As a result, the strength of the deformed Cu/Mg-composite with minimal volume fraction but maximal surface area of magnesium is abnormally high. A thick Cu-sleeve provides low electrical resistivity of this Cu/Mg-composite. The obtained results can be used for the development of high-strength Cu-based conductors.

The existing modeling views allow with particular accuracy to estimate physical and mechanical properties of materials even at the stage of their discussion without long-term procedures of producing and carrying out tests. For example, when estimating composites’ properties, currently, “mixture rule” is widely used that allows calculating strength properties and electrical resistance of composites based on the compositions, which are determined by the components’ volume ratio. It is evident that the “mixture rule”, as all modeling approaches, has its limitations, which the authors would like to estimate using one composite with various volume ratios of the components. Using the fluid extrusion method, three Cu/Mg composite bars were produced, the copper matrix of which contained 1, 7 and 49 thin magnesium fibers. The educated estimates of strength properties and electrical resistance of the deformed composites were carried out using the “mixture rule”. The authors compared the estimated data and the experimental results. It is shown that the fullest conformity of the calculation results with the experimental data can be observed in the composites with 7 and 49 magnesium fibers. In their turn, the estimated strength properties deviate widely from the experiment in the case of practically the same volumes of components in a single-core composite. It is caused by the difference in the mechanisms of deformation of a copper matrix with the FCC lattice and the magnesium HCP-fiber. The results obtained for a composite with the 49 magnesium fibers five the idea of the initial stages of formation of new phases on the Cu/Mg interface in response to the mechanical fusion processes during the severe plastic deformation.

The structure and the mechanical and electrical properties of new ternary composites based on Al‒Mg deformable alloy obtained by fluid extrusion are studied. The evolution of structural and phase transformations in dissimilar fibers (Cu, Mg, and Al–Mg alloy) during thermomechanical treatment are studied using the methods of metallography, scanning electron microscopy, and hardness measurements. It is established that the strengthening of the ternary composite results from solid state reactions at the boundaries of the fiber, which lead to the formation of intermetallide phases (AlCu, Al 2 Cu, Mg 2 Cu, and MgCu 2 ) and nonequilibrium supersaturated solid solutions of copper in aluminum and magnesium.

Two Cu/Mg-composite rods of different content of components were produced by hydrostatic extrusion. The volume proportion of the copper sheath and magnesium core was almost equal in one of the two composite samples. Seven thin magnesium fibers were located in the copper matrix of another composite. Estimate calculations of the strength properties and electrical resistance of deformed composites were carried out and compared with the experimental results. The influence of anneals on the microstructure and electrical and mechanical properties of composites was also studied. This work has shown that a temperature rise causes sequential formation of the intermetallic compounds CuMg2 and Cu2Mg at the Cu/Mg interface, which, according to the phase diagram, results in eutectic reactions. The results of this work can be used in the development of high-strength composite conductors.