Structure and properties of special-purpose alloys after annealing

Special-purpose alloys based on the Al – Si – Cu system are widely used in various industries, including engine and instrument engineering. The effect of annealing in the range of 100 – 900 °C on microstructure, density, and microhardness of Al – 30 % Si – 50 % Cu alloy was studied. Scanning electron microscopy showed that as the annealing temperature increases, the form of eutectic silicon particles changes and their coagulation occurs. According to the results of microrentgenospectral analysis, change in the eutectic structure is accompanied by segregation of copper in its individual sections. After annealing, there is a slight decrease in density and microhardness of the alloy.