Influence of metallurgical parameters and process parameters on the fluidity of Al/SiCp composites by horizontal squeeze casting

摘要

The aim of this study was to investigate the influence of pressure processes parameters, e.g., SiCp contents (0～20wt%), metal mold temperatures, squeeze pressures (8～13MPa/79-132kg/cm{sup}2) and casting thicknesses(representing cooling rate) on the fluidity of three types of Al-matrix SiCp composites (A356/SiCp, A413/SiCp and A390/SiCp). The experimental results indicate that the fluidity of three types of Al-matrix SiCp composites tend to decrease with the increase of SiCp content and increase with the increase of squeeze pressure or mold temperature. When the SiCp content added is more than 5wt% for the A356/SiCp composite, the fluidity will decrease. While, the SiCp content added is more than 10wt% for the A413/SiCp and A390/SiCp composite, the fluidity will decrease. The pressure affecting on fluidity of the composites have a threshold limit value, about 10MPa/106kg/cm{sup}2. Above the threshold limit value, the fluidity is not obviously increased. In addition, the fluidity of composites is also increased with the increase of casting thickness for the composites. Furthermore, the microstructure observations at different positions of strip casting were performed to correlate the solidification modes with the fluidity of three types of Al-matrix SiCp composites. Compared with the matrix alloys, the solidification modes of A356/SiCp alloys do not change for any content of SiCp, but, the modes of A413/SiCp and A390/SiCp alloy do change for any content of SiCp. It is worthily mentioned that the structures at the strip casting of Al-matrix SiCp composites poured at high mold temperature or under high squeeze pressure reveal very fine microstructures.