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Abstract

W-CuO powder mixtures were prepared by attritor mixing/milling of commercial powders. The reduction steps during heating under He/H(2) gas flow were identified by Thermogravimetric Analysis (TGA). W-Cu powder mixtures with 3 different O-content were prepared by adjusting the reduction conditions in a furnace. The effect of O-content on the sintering of powder compacts was then especially investigated. Two sintering steps were identified by dilatometry during liquid phase sintering under He/H(2) atmosphere. The first step was associated to rearrangement after copper melting. The second step was related to the presence of W-oxides at the particle surface: shrinkage was enhanced and the second step was shifted to lower temperatures by using initial powders with low oxygen content, by decreasing the heating rate or by introducing a holding time at 1050°C. This behaviour was related to a gradual reduction of W-oxides from the edge to the bulk of the samples. Microstructural observations were performed at different stages to confirm the analysis. Powder processing and thermal cycle were optimized to obtain materials with 96-97% relative density.

Additional information

Authors: RAHARIJAONA J-J, Laboratoire de Science et Ingénierie des Matériaux et Procédés, Saint-Martin d'Hères (FR);MISSIAEN J-M, Laboratoire de Science et Ingénierie des Matériaux et Procédés, Saint-Martin d'Hères (FR)
Bibliographic Reference: An article published in: International Journal of Refractory Metals and Hard Materials, Article in Press, December 2009
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://dx.doi.org/10.1016/j.ijrmhm.2009.12.004
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