Electron microscopic observation of interfaces of aluminium powder compacts prepared by spark plasma sintering

Aluminium (Al) powder compacts prepared with two kinds of sintering parameters in the spark plasma sintering process have similar density but there is a large difference in their electrical resistivity and tensile properties. The interfaces for the compacts with differing properties were investigated by means of scanning and high-resolution transmission electron microscopy. Two types of interfaces between the powder particles, with metal/metal grain bonding and metal/intermediate oxide film layer/metal grain bonding, were observed in compacts for the two sintering conditions. The properties of Al powder compacts were mainly attributed to the behaviour of oxide film between the particles. It was observed that in the compact containing many metal/metal grain bonding interfaces, the electrical resistivity was lower and the tensile properties were better.