MICROSTRUCTURAL ANALYSIS OF HOT ISOSTATICALLY PRESSED AL-SIC

The difference between extruded and hot isostatically pressed (HIP) Al6061 both with a T6 final heat treatment and with a 30 wt.% SiC particulate reinforcement is one of densification. The higher density of the HIP material is not translated into a stronger material. The Mg2Si precipitation is favoured by the presence of the SiC reinforcement in both samples. HIP powder metallurgy material reveals clearly the original powder particle boundaries, in contrast to the more smeared-out stringers in the extruded material. Cleavage of SiC particles by neighbouring SiC particles is observed in the HIP samples, making them less ductile.