INFLUENCE OF HEAT TREATMENT MODES ON THE TRANSIENT ELECTRICAL RESISTANCE OF COPPER-ALUMINUM BIMETAL OBTAINED BY EXPLOSION WELDING

The paper presents the results of a comprehensive study of the effect of heat treatment modes on the value of transient electrical resistance and structural changes in bimetallic copper-aluminum samples obtained by explosion welding. The main objective of the study is to find out the optimal mode of heat treatment of copper-aluminum bimetal obtained by explosion welding in order to achieve a minimum transient electrical resistance due to the balance between de-riveting and suppressing the growth of the intermetallic phases. The task to which the paper is devoted is to establish quantitative dependences of the transient electrical resistance of copper-aluminum bimetal on the parameters of heat treatment and to study the correlation between the resistance value and structural changes in the transition zone. The research methods used include comparative analysis at the stage of determining the relevance of the work, precision micrometry, evaluation of the microstructure of the material, methods for quantifying the dependence of the transient resistance of the composite on temperature and annealing time. The novelty of the work is in finding an optimal heat treatment mode that ensures the minimum transient resistance of copper-aluminum bimetal obtained by explosion welding compared with bimetal manufactured using traditional technologies. The results of the study show that the amount of resistance is determined by the competition of two processes: deriveting, which leads to a decrease in resistance, and the growth of intermetallic phases, which cause its increase. The optimal mode of heat treatment (heating to 350 °C with exposure in the furnace for 45 minutes), providing a minimum transient resistance of 1.12 microhm, is identified. A comparative study with industrial analogues of the copper-aluminum composite show that the transient resistance of the developed bimetal is 2-2.5 times lower than that of transformer windings manufactured using traditional technologies.