COUPLING BETWEEN SINTERING AND LIQUID MIGRATION TO PROCESS TUNGSTEN-COPPER FUNCTIONALLY GRADED MATERIALS

The aim of this study is to analyze the mechanisms of liquid migration in the course of liquid phase sintering of W-Cu composition-graded components, in order to control the final composition profile. W-Cu materials with 10 and 20wt%Cu and with two different W-particle sizes were processed starting with attritor-milled W-CuO powder mixtures which were reduced at 350 degrees C. Analysis of liquid phase migration for different composition/grain size associations indicates that the phenomenon is driven by differential sinterability in the gradient. Cu-liquid migration occurred from the layer with high sinterability to the layer with low sinterability. So, the liquid migration depends on the differences in sinterability, on the available liquid and open porosity in the layers beyond the melting point of copper. From these analyses, a way to control the gradient profile of W-Cu structure can be proposed. Cu-liquid migration may also be used to improve the densification in the graded material structure by a kind of in situ infiltration process. Depending on the composition/grain size association, a smoothed composition profile or a stairway composition profile can be obtained. This work will be used to process W-Cu functionally graded materials (FGM) for fusion technology, in particular high heat flux components so called plasma facing components (PFC).