Aluminum nitride/metal composites using ultra-fine aluminum particles and their application for joining

Composite blocks of the system M-AlN (M = Al, Ni, etc.) were prepared by the method of powder metallurgy. A raw material i.e. ultra-fine Al particles, was prepared by means of arc-plasma processing. A mixture of the ultra-fine Al particles and metal powders was pressed (200 MPa) in a steel die followed by two-step sintering (873 and 1273 K) in flowing nitrogen. The properties of the composite such as structure, density, thermal expansion coefficient and micro-hardness were examined. Mixtures of the ultra-fine Al particles and a commercial coarse Al powder were pressed (200 MPa) in a steel die. These green compacts were put on AlN plates followed by heating (873 K) in flowing nitrogen. The joining of the AlN plate and the composite of Al-AlN were accomplished completely. Chemical analysis of the material in the vicinity of the interlayer, which was carried out by means of EPMA, indicated that an Al metal layer was formed along the interface, this Al metal layer acting as a brazing material. Also, the joining of Fe/FGM of Al-AlN was achieved completely.