Topic
Tungsten
About: Tungsten is a research topic. Over the lifetime, 35225 publications have been published within this topic receiving 456213 citations. The topic is also known as: W & element 74.
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TL;DR: In this paper, it was found that the addition of Y2O3 nano-particles could significantly hinder the grain growth of tungsten in the consolidation process, decreasing the average grain size from 3.2μm in pure W down to 0.7μm.
90 citations
TL;DR: In this article, an optimized sintering atmosphere was used to sinter two heavy alloy compositions (88 and 95 wt pct W) for times up to 600 minutes at 1480 °C.
Abstract: The mechanical properties of tungsten heavy alloys are sensitive to the processing cycle and are adversely affected by residual porosity. Sintering times greater than 2 hours usually result in pore growth with degraded properties. The development of an optimized sintering atmosphere has allowed exploration of long sintering times without significant property degradation due to pore growth. The optimal cycle was used to sinter two heavy alloy compositions (88 and 95 wt pct W) for times up to 600 minutes at 1480 °C. The 88 pct W samples slumped, but the 95 pct W samples were fully densified and suitable for tensile testing. At long sintering times, the tungsten grains flattened and the tungsten contiguity decreased, indicating a transition to low-energy configurations for the solid-liquid interfaces. The cube of the mean grain size varied linearly with the isothermal sintering time. This allowed determination of grain size effects on mechanical properties, showing a decreasing yield strength with increasing time in agreement with the Hall-Petch behavior. The tensile strength and elongation were highest for sintering times from 30 to 90 minutes, reflecting a minimum in the residual porosity.
90 citations
15 Sep 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of mixing technique and particle characteristics on the rheology and agglomerate dispersion of tungsten-based powder injection molding (PIM) feedstock was investigated.
Abstract: This study investigates the effect of mixing technique and particle characteristics on the rheology and agglomerate dispersion of tungsten-based powder injection molding (PIM) feedstock. Experiments were conducted with as-received (agglomerated) and rod-milled (deagglomerated) tungsten powder mixed in a paraffin wax–polypropylene binder. Increase in the mixing shear rate decreased the agglomerate size of the agglomerated tungsten powder, decreased the viscosity, and improved the flow stability of the feedstock, interpreted as increased homogeneity of the feedstock. Higher solids volume fraction, lower mixing torques, and improved homogeneity were observed with deagglomerated tungsten powder, emphasizing the importance of particle characteristics and mixing procedures in the PIM process. Hydrodynamic stress due to mixing and the cohesive strength of the tungsten agglomerate were calculated to understand the mechanism of deagglomeration and quantify the effect of mixing. It was concluded that deagglomeration occurs due to a combination of rupture and erosion with the local hydrodynamic stresses exceeding the cohesive strength of the agglomerate.
90 citations
TL;DR: In this paper, X-ray diffraction of pure tungsten and nearly stoichiometric ZrC, ZrN, TiC, and TiN has been investigated.
90 citations
Abstract: The emission angular distribution, total energy distribution, noise spectrum, and emitter life have been measured for the W/Zr thermal‐field cathode The results give an emitter life in excess of 1000 h at T=1350 to 1450 K, P?2×10−8 Torr, and a total current of ∼100 μA A low‐noise highly confined beam long the (100) direction can be obtained A source brightness of 1010 A/cm2 sr at 3 kV and an energy spread of less than 09 eV were measured under operational conditions
90 citations