Fabrication And Characterisation Of Copper Composites Reinforced With Transition Metal Carbides Via Mechanical Alloying
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Date
2011-01
Authors
Mohd Subhi, Nur Hawadah
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
In this study, high-energy ball milling also called mechanical alloying (MA) was applied
to synthesis in situ copper based composite. Cu, M (M=W or Ti) and graphite powder
mixture were mechanically alloyed for various milling time in a planetary ball mill. The
nominal composition was Cu-28.72wt%W-1.87wt%C and Cu-9.67wt%Ti-2.42wt%C
which corresponds to Cu-20vol%WC and Cu-20vol%TiC, respectively. With similar
composition and milling time, the ex situ WC and TiC reinforced copper composite was
also mixed by ball milling. Then the as-milled powder for both in situ and ex situ
composites were compacted at 200 to 400 MPa and sintered in vacuum furnace at 900ÂșC.
The results of X-ray diffraction, scanning electron microscopy and energy dispersive
spectroscopy analysis showed that formation of tungsten carbide (W2C and WC phases)
observed after sintering of Cu-W-C composite while TiC precipitated in as-milled
powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling.
Mechanism of MA explained the cold welding and fracturing event during milling. Cu-
W-C system shows fracturing event is more dominant at early stage of milling and W
particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is
more dominant and all Ti particles dissolved into Cu matrix. These phenomena results in
increased the microhardness properties of both in situ Cu-W-C and Cu-Ti-C composite
and decreased in electrical conductivity by increasing the milling time. Higher
microhardness and lower electrical conductivity are obtained in both in situ composite
compared to ex situ composite due to the effect of MA and the fine carbides particles
precipitation.
Description
Keywords
Mechanical alloying (MA) was applied , to synthesis in situ copper based composite