Investigation on microstructure of Al–25 wt-%Mg2Si composite produced by slope casting and semi-solid forming

Abstract

The effect of cooling slope casting process and semi-solid forming on the microstructure of Al–Mg2Si composite were investigated. In the current work, in order to obtain a suitable microstructure for semi-solid forming process, including good sphericity of α-Al phase with the equivalent diameter of less than 100 μm, cooling slope method was used. Cooling curve of cast composite was plotted using thermal analysis method. Nucleation temperature of each phase was determined using the first derivative curve and cooling curve. Casting was performed at three different temperatures to find the best temperature for casting on the cooling slope. Approriate temperature for reheating in semi-solid range was determined using solid fraction curve. Samples obtained from cooling slope process were thixoformed. The results showed that the microstructure was improved in the thixoformed samples.