The effect of thermomechanical parameters on the eutectic silicon characteristics in a non-modified cast A356 aluminum alloy

The influence of hot working parameters on the microstructural evolution of cast A356 aluminum alloy has been studied emphasizing the changes in eutectic phase morphology. Toward this end, a set of isothermal compression tests were conducted in the temperature range of 400–540 °C. The results indicate that the eutectic Si platelets are fragmented, spheroidized and also evenly distributed in the matrix as a result of applying proper thermomechanical cycles. The mechanical fragmentation and thermal disintegration play a prominent role in Si particles breaking up under the different deformation conditions, whereas the average particle size is decreased with decreasing the temperature and increasing the strain rate. The lowest shape factor and aspect ratio are also achieved for the specimens deformed at higher temperatures and lower strain rates. The current work also explores the high temperature flow behavior of cast A356 alloy to address the dominant restoration processes taken place at different thermomechanical conditions.