graded structure and interface quality on thermal behavior of Cu-W FGM. 
2.Experimental methods 
Two tungsten powders (mean particle size of 22um and 12pm, by Plansee) and a copper 
powder (mean particle size of 22,8um, by Merck), have been selected for this study. Typical 
scanning electron micrographs are shown in Fig. 1. The powders have been pre-treated by mixing in 
a rotary mill for the uniaxial pressing. To avoid demixing the filled volume was not more than 25% 
of total mixer volume. 
Figl. SEM micrographs of copper powder with dendritic shape produced by electolytic technique (a), and 
tungsten powder 22pm (b), 12pm (¢) with polygonal shape produce by gas reduction. 
Samples with different mixture ratios have been cold pressed in the range of 330MPa- 
1,3GPa. The choice of the consolidation conditions depends on the concentration area of the Cu-W 
gradient. Pressureless sintering of individual layers was performed in inert atmosphere at 1150°C, 
for 3h. Three layer gradient (Cu/50Cu+50W/W) and six layer gradient 
Cu/80Cu+20W/60Cu+40W/40Cu+60W/20Cu+80W/W) with diameter of 8 mm, are produced by 
hot pressing in 750 °C with applied pressure of 70 MPa in protective atmosphere. 
Electron beam tests (JUDITH) on the 3 and the 6 layer compositions of copper-tungsten 
FGM have been performed. The materials have been exposed to effective pulse duration of 5 ms 
with deposited energy densities of 4,2 MJ/m? on a surface area of 5x5 mm’. After electron beam 
test the surface and cross section of the sample have been analysed by optical and scanning 
microscopy 
Measurement of electrical resistivity in four point , has been used in order to investigate 
influence of interface quality on electrical and thermal conductivity. 
3.Results and Discussion 
From the microstructural point of view, in Cu-W FGM (Fig. 2) a transition from a dispersive 
microstructure near the copper and tungsten reach side, to a network in the intermediate 
composition range occurs. This is typical continuous percolation transition. In the Cu-W solid phase 
sintered gradients, the porosity depends strongly on the content relation of Cu-W. In concentration 
area with more than 60 Vol % Cu the density of the specimens is satisfactory. Above this 
concentration values porosity will influence the material properties. 
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