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The uneven distribution and large size of the second phase weakens the effect of dispersion strengthening in ODS-W alloys. In this article, the W-Al2O3 composite powders were fabricated using a wet chemical method, resulting in a finer powder and uniformly dispersed Al2O3 particles in the tungsten-based alloy. The particle size of the pure tungsten powder is 1.05 μm and the particle size of W-0.2 wt.%Al2O3 is 727 nm. Subsequently, the W-Al2O3 alloy plates were successfully obtained by induction sintering and rolling processes. Al2O3 effectively refined grain size from powder-making to sintering. The micro-hardness of the tungsten alloy plates reached 512 HV0.2, which is 43.7% higher than that of pure tungsten plates. The nano-hardness reached 14.2 GPa, which is 24.1% higher than that of the pure tungsten plate; the compressive strength reached 2224 MPa, which is 37.2% higher than that of the pure tungsten. [ABSTRACT FROM AUTHOR]

Pure tungsten and tungsten alloys with 1, 2, and 3 wt.% Lu 2 O 3 were fabricated by mechanical alloying and spark plasma sintering at 1600 °C for 3 min. These samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive spectroscopy, Vickers microhardness, thermal conductivity analyses, thermal shock test, and deuterium retention. Results revealed that the microhardnesses of the samples have a similar trend with the relative density. With increased the doped Lu 2 O 3 content, the relative density and microhardness increased and the Lu 2 O 3 particles significantly increased the density and strengthened of tungsten alloy. With increased temperature from 300–1100 K, the thermal conductivity decreased with increased Lu 2 O 3 content. The doped Lu 2 O 3 particles revealed good enhancement effect in the thermal shock resistance and a good influence in the deuterium retention. [ABSTRACT FROM AUTHOR]

In previous researches, there are few studies on the mechanisms involved in liquid-liquid doping techniques for preparing oxide particle doped tungsten powders. In this research, based on different polytungstate species, three liquid–liquid doping techniques for synthesizing different doped precursor powders were proposed and compared. The extremely homogeneous hexagonal (NH 4) 0.33 WO 3 ·H 2 O microspheres and flaky (NH 4) 6 H 2 W 12 O 40 ·5H 2 O were synthesized. The synthesis mechanisms of precursors, the doping processes and reaction mechanisms for preparing yttrium-stabilised ZrO 2 in ternary liquid phase system were discussed. The doped powder prepared through azeotropic distillation method exhibits higher quality due to the highly dispersed ZrO 2 (Y) phase uniformly distributed in flaky precursor, and the corresponding alloy possesses more excellent microstructure and mechanical properties. The proposed azeotropic distillation method offers a general pathway and is readily adapted to large-scale industrial production of high-quality oxide particle doped W powders. Image 1 • Three novel liquid–liquid doping technique for preparing precursors were proposed. • Extremely homogeneous microspherical and flaky precursors were synthesized. • Synthesis mechanism of three precursors were investigated in detail, respectively. • Reaction mechanisms for synthesizing cubic ZrO 2 in ternary liquid system were discussed. • Novel method offers a general pathway in industrial production of high quality ODS-W powders. [ABSTRACT FROM AUTHOR]

Oxide dispersion strengthened tungsten (ODS-W) alloys are a class of important materials that widely used for high temperature applications due to their unique physical and mechanical properties. However, the insufficient ductility of ODS-W alloys at low or high temperatures limits their widespread application, especially as structural materials. It is always a great challenge to efficiently disperse oxide second phase nanoparticles within W matrix for achieving ODS-W alloy with excellent balance of strength and ductility. Here we report an innovative strategy for the fabrication of high-performance ODS-W alloy with strength of up to 1134 MPa and total elongation over 30% at 700 °C. The innovative route involves the preparation of W–Y 2 O 3 composite powder precursor via alkaline hydrothermal method and subsequent low-temperature sintering in hydrogen atmosphere. The internal flake structure with uniformly dispersed Y component and external coating of W component on this flake structure can be formed in alkaline hydrothermal product and then be passed on to the reduced W–Y 2 O 3 composite nanopowders. As a result, the distribution of second phase oxide particles in the low-temperature sintered alloys using these composite nanopowders as precursor is optimized significantly including an increase in the volume fraction of intragranular oxide particles and a decrease in the size of both intergranular and intragranular oxide particles. Besides, the average W grain size is also refined dramatically (410 nm). More importantly, the intragranular oxide particle / W matrix interface is regulated to be coherent relationship. The combined action of these microstructural factors is responsible for the significantly enhanced strength and ductility of ODS-W alloy. These results indicate that the newly developed alkaline hydrothermal method in our work is a promising way to fabricate high performance ODS tungsten based alloys. [ABSTRACT FROM AUTHOR]