Formation of aluminium nitride during sintering of powder injection moulded aluminium

A detailed transmission electron microscopy study of the structure of aluminium nitride formed during sintering of powder injection moulded aluminium is presented. A polycrystalline layer formed on Al particle surfaces exposed to a nitrogen atmosphere. This layer consisted of fine, rod-like crystallites of hexagonal AlN typically aligned normal to the Al surface. A double layer of AlN separated by a thin layer of Al was observed at the interfaces between Al grains. In this report, the structure of the nitride is characterised and its influence on sintering is discussed.