PRINCIPLES OF FUNCTIONAL GRADIENT MATERIALS AND THEIR PROCESSING BY POWDER-METALLURGY

The principles of a new class of materials with an artificial inhomoge neity have been developed and their fabrication methods have been stud ied, The theoretical basis of these functional gradient materials (FGM s), their three-dimensional structure and properties evaluation, and e xperimental powder metallurgy techniques of their processing, based of melt infiltration in combination with chemical liquid deposition and microgravity forming, have been investigated. The W-Cu-Ag-Cr-Diamond, WC-Co, ceramics (Si3N4, SiC) - metal (Cu, Al) systems were studied for FGM components manufacturing. The behaviour of materials during infil tration has been examined with a laboratory scale high temperature the rmal balance. The apparatus and theoretical background for the descrip tion of a measured signal (apparent thermogravimetry technique) have b een adapted to simulate the condition of the process for different FGM systems by infiltration. The structure and properties of FGMs were ev aluated with the micromechanical model developed, and special software was designed for that. The results of the present study are part of t he COST 503/III project - ''Powder based gradient materials and compon ents'', supported by the Commission of the European Communities (DG-XI I, Joint Research Centre).