Microstructures and Properties of Hypoeutectic Al-Si Alloy Extruded in Semi-Solid State
The microstructures and properties of AlSi7Mg alloy extruded at 575°C in semi-solid state were studied for analyzing the extruding feasibility of the casting aluminum alloy in high solid fraction. The results show that the microstructure of AlSi7Mg alloy through low-superheat direct chill (DC) casting mainly consists of the homogeneous, fine rosette-shaped grains. The microstructure of the billet reheated at 575°C in 15min is composed of stable and near- spherical grains, which are suitable for thixoforming in high solid fraction. Extruded at 575°C in the semi-solid state, the facial-smoothed parts of AlSi7Mg alloy with homogeneous, fine microstructure across the section is obtained, and the properties of extruded part are improved obviously.