Microstructure, Phase Composition, Substructure and Residual Stress of Aluminum Alloy AK5M7 after Its Electro Spark Treatment
This paper presents the results of a study of the microstructure, phase composition, substructure parameters and residual stresses of the surface layer of the AK5M7 alloy after electrospark treatment (EST) using a copper-phosphorus electrode. EST energy constitutes the main variable parameter while the material under study is a multiphase alloy. The materials under phase study are: Al, Al<sub>2</sub>Cu and Cu<sub>3</sub>Al. It was found that an increase in the EST energy is accompanied by an increase in the proportions of Al<sub>2</sub>Cu and Cu<sub>3</sub>Al. As well as an increase in the magnitude of microstrains and residual stresses, followed by a decrease in the size of subblocks. For the aluminum phase, residual stresses are tensile, while for Al<sub>2</sub>Cu, they are compressive. Analysis of the intensities of the diffraction lines indicates the possibility of texture in the processed layer. An increase in the EST energy leads to a chaotic distribution of the grain orientation of the generated crystallographic phases. The results obtained are explained by nonequilibrium processes in the near-surface layer under high mechanical and thermal influences, accompanied by micrometallurgical processes.