Morphological and Thermal Flux Analysis in as-Cast Al Alloy after Swarf Addition

Abstract

In this research, effect of swarf addition on the microstructure of die cast aluminum A380 alloy and the possibility of altering the alloy structure in the metallic die has been studied. The microstructure mainly consists of the α-phase, eutectic, intermetallic compounds and porosity. Since the alloy solidifies under non-equilibrium conditions, the Scheil equation with exact amount of equilibrium distribution, analyzed by SEM-Line scan around an intermetallic phase at different mixing times as well as governing equations of thermal analysis, was used to calculate the solid weight fraction. Finally, using the thermal flux analysis in the crucible, a scientific prediction on the optimal amount of swarf addition, mixing time and temperature, was made. The shape factor at an optimum temperature of 590 °C was measured as 0.643. According to the optical microscope images of the die cast samples, the addition method (adding it to the floor or to the surface) and increasing the injection temperature have a significant effect on the solid weight fraction, morphology of the α-phases and final microstructure of the alloy.

Keywords

• semi-solid casting
• microstructure
• solid fraction
• swarf
• solidification.