Full Densification of Loosely Packed W–Cu Composite Powders

Abstract

The metal injection moulding (MIM) technique appears to have potential for mass production of small and delicately shaped W–Cu parts, primarily for microelectronics, although problems in densification, owing to the inherently poor sinterability of the W–Cu system as well as the low volume fraction of MIM debound parts, need to be overcome. Several attempts have been made to attain full densification of the loosely packed W–Cu composite powders in MIM brown parts. The use of the nanocomposite W–Cu powders, prepared either by coreduction of fine Wand Cu oxide powder or by mechanical alloying of Wand Cu powders, was shown to enhance the sinterability, resulting in the full densification of W–Cu MIM parts. Similar effects were observed in the case of tailored W–Cu powder mixtures with high mixing homogeneity and packing density. The high sinterability of the pertinent W–Cu systems is attributed partly to the nanosintering effect, owing to the intrinsic homogeneous and fine mixed state of the W–Cu phases, and partly to activated sintering which is promoted by impurities introduced during the extensive milling process. PM/0768