High-temperature backward extrusion forming of aluminum matrix composite cup-shaped parts with high volume fraction of SiCp

An aluminum matrix composite with high volume fraction of SiCp was prepared by pressureless infiltration.Cup-shaped parts were made of the SiCp/Al composite by using high temperature backward extrusion.The flow stress behavior of the SiCp/Al composite during hot backward extrusion was investigated.The effects of hot backward extrusion parameters on the microstructure of the SiCp/Al composite were observed and analyzed by SEM.The results show that at temperatures above the melting point of aluminum matrix the SiCp/Al composite is a viscous fluid,SiC particles and aluminum matrix form into a solid-liquid mixture.When the SiCp/Al composite is backward extruded at high temperature,aluminum matrix remains continuous,but SiC particles roll over and rearrange under pressure,some particles break,and the particle distribution uniformity is good.As the deformation temperature is lower and the extrusion speed is rapider,SiC particles are easy to break,the internal particle size distribution of SiCp/Al composite cup-shaped parts is nonuniform,and the particle size is smaller in the internal angle position of cup-shaped parts.The particle size uniformly distributes at a higher temperature and a smaller extrusion speed.