Physicochemical properties of ball milled boron particles: Dry vs. wet ball milling process

Fabrication and characterization of Ni–W solid solution alloys via mechanical alloying and pressureless sintering

Powder metallurgy technique was employed to prepare W–30 wt.% Cu composite through a chemical procedure. This includes powder pre-treatment followed by deposition of electroless Cu plating on the surface of the pre-treated W powder. The composite powder and W–30Cu composite were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Cold compaction was carried out under pressures ranging from 200 MPa to 600 MPa while sintering at 850 °C, 1000 °C and 1200 °C. The relative density, hardness, compressive strength, and electrical conductivity of the sintered samples were investigated. The results show that the relative sintered density of the titled composites increased with the sintering temperature. However, in solid sintering, the relative density increased with pressure. At 1200 °C and 400 MPa, the liquid-sintered specimen exhibited optimum performance, with the relative density reaching as high as 95.04% and superior electrical conductivity of IACS 53.24%, which doubles the national average of 26.77%. The FE-SEM microstructure evaluation of the sintered compacts showed homogenous dispersion of Cu and W and a Cu network all over the structure.

Sintering behavior of W–30Cu composite powder prepared by electroless plating

Preparation and properties of superfine W–20Cu powders by a novel chemical method

This book is focused on composites involving powders as the starting materials. It provides relevant information for questions related to the selection of constituent phases, most economic fabrication routes, proper testing procedures, and product optimization. The field is sufficiently advanced that predictive models guide many decisions. Applications are illustrated over a broad range of material and property combinations. This title includes: Selection of phases with consideration of intersolubility & interface Microstructure, especially the role of phase connectivity Fabrication approaches, especially net-shape consolidation Assessment of typical properties, testing techniques & industry standards Design & trade-off decisions involved in optimization, including cost Applications, both those that have matured and some emerging prospects. The reader may have little appreciation for how particulate composites are literally everywhere. Examples include new wear resistant consumer products(Apple watch), longer lasting automotive tires with reduced rolling resistance(Yokohama tires), and new diamond heat sinks for computers(Element Six substrates). Particulate composites also form critical components in applications such as magnets, dental fillings, brakes, darts, bio-implants, & cutting tools. Particulate composites are a multi-billion dollar industry, and can be a cost-effective solution ripe for innovation and continued rapid growth. For the engineer, the wide range of particulate composite formulation and property combinations offers the ability to design for a variety of application and provides ample opportunity for innovation. Particulate Composites: Fundamentals & Applications is ideal for use in a one-semester eng. course at the senior UG/graduate level, and is also suitable as a practical reference for materials scientists in academia and industry

Particulate Composites : Fundamentals and Applications

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 mill...

Effects of wet and dry milling conditions on properties of mechanically alloyed and sintered W–C and W–B4C–C composites

Powders with a composition of 85W–15Cu (wt-%) were prepared by mixing, milling and mechanical alloying of W and Cu powders and electroless Cu coating onto W powder. Sinterability was improved by mechanical alloying and coating. The improvement due to mechanical alloying comes from a reduced particle size, assisted by activated sintering from transition element contamination in milling. Coating improved the copper dispersion, packing densities and led to a microstructure having reduced number of W–W particle contacts after compaction. Accordingly, rearrangement on liquid formation resulted in improved densification. Since copper wetting on tungsten is sensitive to oxygen contamination, coated powders ensure liquid copper dispersion throughout the compact without concern over wetting and liquid flow during liquid phase sintering.

M. L. Öveçoğlu

Papers

Effects of wet and dry milling conditions on properties of mechanically alloyed and sintered W–C and W–B4C–C composites

Comparative properties of 85W–15Cu powders prepared using mixing, milling and coating techniques