Papers by Author: J.M. Missiaen

Abstract: This paper presents a detailed study of large grains carried out by transmission electron microscopy in two WC-Co alloys, one W rich and the other C rich. In the W rich alloy, some large grains are found in contact with the η phase while no connection of the large grains with graphite particles can be pointed out in the C rich alloy. The C content greatly influences the morphology of large grains: they are flatter in the C rich alloy with smoother interfaces. Whatever the C content, they contain few dislocations compared to matrix grains except in a small area where a dense network is often present. One or even several small WC grains with a small angle misorientation or with a Σ=2 coincidence relationship are often found inside the large grains. They have likely been engulfed during the growth of the large grains owing to the low boundary energy.

Abstract: Processing of W-Cu graded materials from attritor-milled W-CuO mixtures is described. The powder reduction steps are investigated by TG and XRD analyses and by microstructural observations (SEM, TEM). Sintering of reduced powder with different compositions is analysed by dilatometry. Sintering behaviour of the graded component processed by co-compaction of a 10/20/30wt%Cu multi-layer material is briefly discussed. Liquid Cu migration is observed and smoothes the composition gradient. Perspectives to control this migration are discussed.