Effects of wet and dry milling conditions on properties of mechanically alloyed and sintered W-C and W-B4C-C composites
Authors: Ünal, N.1; Öveçoğlu, M.L.2
Source: Powder Metallurgy, Volume 52, Number 3, September 2009 , pp. 254-265(12)
Publisher: Maney Publishing
Abstract:
Tungsten based W-1C and W-2B4C-1C (wt-%) powders synthesised by mechanical alloying (MA) for milling durations of 10, 20 and 30 h, in wet (ethanol) and dry conditions, were characterised. X-ray fluorescence spectroscopy investigations revealed Co contamination which increased with increasing milling time during wet milling. X-ray diffraction investigations revealed the presence of W and WC phases in all powders, Co3C intermetallic in the wet milled W-1C powders and W2B intermetallic phase in both wet and dry milled W-2B4C-1C powders. As blended and MA processed powders were consolidated into green compacts by uniaxial cold pressing at 500 MPa and solid phase sintered at 1680°C under hydrogen and argon atmospheres for 1 h. X-ray diffraction investigations revealed the presence of W2C intermetallic phase in sintered composites produced from both wet and dry milled W-1C powders and the W2B intermetallic phase in sintered material from the wet milled W-2B4C-1C powder. Sintered composites from wet milled powders showed relative densities >91%, with the maximum density of 99·5% measured for the sintered 30 h wet milled W-2B4C-1C composites. Microhardness values for the wet milled W-1C and W-2B4C-1C composites were 2-2·5 times higher than those for dry milled composite powders. A maximum hardness value of 23·7±2·1 GPa was measured for the sintered W-2B4C-1C composite wet milled for 20 h.Keywords: MECHANICAL ALLOYING; TUNGSTEN; BORON CARBIDE; SINTERING; CHARACTERISATION
Document Type: Research article
DOI: 10.1179/003258909X12490463446434
Affiliations: 1: Department of Metallurgical and Materials Engineering, Faculty of Chemistry-Metallurgy, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey;, Email: nil_unal@yahoo.com 2: Department of Metallurgical and Materials Engineering, Faculty of Chemistry-Metallurgy, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey

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