Functionally gradient materials of the system AIN-metals

A functionally gradient material block of the system AIN-M (M=Ni, Mo, W) was prepared by the method of powder metallurgy. The raw materials i.e. ultrafine particles were prepared by means of the arc-plasma processing. A compositionally gradient mixture of an ultrafine aluminum particle and M particle was pressed (200-400 MPa) in a steel die, followed by two-step sintering (873 K and 1273 K) in flowing nitrogen under null pressure. The techniques of an ultrafine-particle mixing and a sintering process with no crystal-grain growth were invented. The nitriding reaction of aluminum is exothermic, thus, it considerably progresses by self-propagating high temperature synthesis when it has once begun. The structures and the compositional gradient of the FGM block were examined by SEM, EDX, EPMA and XRD. The properties of the FGM blocks such as density, thermal expansion coefficient and microhardness etc. were measured.