Reheating process for thixoforging of metal matrix composites fabricated by induction heating and the mechanical stirring process

Abstract

Abstract

The forming process of metal matrix composites by the die casting and squeeze casting process is limited in size and dimension in terms of final parts. The melt stirring method has problems owing to the fact that the homogeneous distribution of the reinforcements is difficult due to low weldability and the density difference between the molten metal and the reinforcement. The thixoforming process for metal matrix composites has numerous advantages compared to die casting, squeeze casting and compocasting. However, for the thixoforming process, the billet with the desired volume fraction must be heated to obtain a uniform temperature distribution over the entire cross-sectional area.

To obtain the reheating conditions of composites, the particulate reinforced metal matrix composites for thixoforming were fabricated by a combined stirring process with simultaneous electromagnetic and mechanical stirring. The matrix alloy and reinforcement were aluminium alloy (A357) and SiC particle with diameters of 14 and 25 üm respectively. The microstructure characteristics were investigated by changing the volume fraction and reinforcement size. The reheating conditions used to obtain the uniform temperature distribution over the cross-sectional area of the fabricated metal matrix composites billet were suggested with variations in the heating time, the heating temperature and the holding time.