Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province

Hefei, China

Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province

Hefei, China
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Wang K.,Hefei University of Technology | Zan X.,Hefei University of Technology | Zan X.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Yu M.,Hefei University of Technology | And 6 more authors.
Fusion Engineering and Design | Year: 2016

Investigations are conducted of the recrystallization behavior of pure tungsten through different thickness reductions by isothermal annealing at 1350°C. Concise description is made of the recrystallization kinetics by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model in combination with hardness test results. The rate of the recrystallization process increases with the deformation ratio. For further investigations, three boundary maps of tungsten plates which are of different thickness reductions by rolling and in full recrystallization are obtained, each covering an area of 1.15×1.05mm2 on the transversal section comprising the rolling direction (RD) and the normal direction (ND). The average grain size and its distribution of pure tungsten can be easily calculated, and hence the grain aspect ratios of pure tungsten. © 2017 Elsevier B.V.


Lin J.-S.,Hefei University of Technology | Luo L.-M.,Hefei University of Technology | Luo L.-M.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Xu Q.,Kyoto University | And 6 more authors.
Journal of Nuclear Materials | Year: 2017

W–3Lu2O3 composites were prepared by mechanical milling and spark plasma sintering. The obtained composites were subjected to He+ irradiation experiments. The irradiated samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and measurement of Vickers hardness. Thermal desorption spectroscopy analysis was performed to analyze the samples at different damage levels after Fe2+ and D+ irradiation. Results showed varied degrees of He+ damage under different energies. Fuzz structures were observed on the surface of the material after irradiation. TEM results indicated that the existence of these fuzz structures was related to the formation of He bubbles. Amorphous, polycrystalline, and γ-W phases formed in areas where He bubbles existed. The measured Vickers hardness proved that radiation hardening occurred after irradiation. After Fe2+ irradiation at different damage levels, the total retained deuterium amount of W–3Lu2O3 and pure W differed, and the impact of Fe2+ radiation for deuterium retention on pure tungsten was greater. © 2017 Elsevier B.V.


Yu M.,Hefei University of Technology | Wang K.,Hefei University of Technology | Zan X.,Hefei University of Technology | Zan X.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | And 6 more authors.
Fusion Engineering and Design | Year: 2016

Tungsten is a promising plasma-facing material because of its low sputtering yield, high melting point and high thermal conductivity. The hardness loss and microstructure evolution of pure tungsten hot-rolled to 90% thickness reduction is investigated by isothermal annealing at temperature range of 1200-1350. °C. Changes in the mechanical properties caused by recovery and recrystallization during heat treatment are detected by Vickers hardness measurements. Additionally, the microstructural evolution is analyzed with light optical microscopy and X-ray diffraction. The results indicate that the hardness evolution can be divided into two stages: recovery and recrystallization. Recrystallization of W90 in the temperature range of 1200 to1350 °C is governed by the same activation energy as grain boundary diffusion. The average recrystallized grain size is larger for lower annealing temperatures. © 2017 Elsevier B.V.


Luo L.,Hefei University of Technology | Luo L.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Lu Z.,Hefei University of Technology | Li H.,Hefei University of Technology | And 5 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2013

Because of its high melting point, high strength, low vapor pressure, low sputter etching rate, good thermal stability and high strength ductility and excellent comprehensive properties, tungsten alloys were widely used in national defense, aerospace, metallurgy, electronics and other fields. However, tungsten alloys also existed a variety of problems, such as low recrystallized temperature, high ductile-brittle transition temperature (DBTT) and low temperature strength. Moreover, as the vitamin for metal, the rare earth elements with their unique properties could refine grain, effectively purify grain boundaries, and make the material improve to a great extent. Therefore, adding rare earth elements into tungsten alloys for improving mechanical properties of tungsten alloys became one of the hottest researches. This review introduced the function and the mechanism of the rare earth elements in tungsten alloys (W-Cu alloys, W-Ni-Fe (Cu) alloy, W-TiC alloy and the tungsten in the electrode) and came up with some problems on it and also pointed out how it developed in future.


Zhao M.-L.,Hefei University of Technology | Luo L.-M.,Hefei University of Technology | Luo L.-M.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Li H.,Hefei University of Technology | And 4 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

TiC powders were pretreated by chemical activation, and then Ni-W-coated TiC composite powders were synthesized by electroless plating process. The powders consist of 2%(mass fraction) Ni-W-coated TiC composite powders and pure W powders were pressed under different pressures and sintered to W-Ni/TiC bulk composites. The microstructure and compositions of the initial TiC powders, the pretreated TiC powders, the Ni-W-coated TiC powders and the W-Ni/TiC composites were analyzed by scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS). The formation process of Ni-W-coated TiC powders and W-Ni/TiC composites, and the influence law of pressure on the sintered body were discussed. The results show that Ni-W coated TiC uniformly by electroless plating progress. W-Ni/TiC composites have higher density than that of pure W sintered body by the same process, and the higher pressure on compacts, the higher density of the composites can be obtained. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.


Luo L.-M.,Hefei University of Technology | Luo L.-M.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Chen J.-B.,Hefei University of Technology | Wang Z.-C.,Hefei University of Technology | And 5 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2014

Activitation treatment for PC plastic substrate by using nitric acid before electroless plating was carried out, then PC plastic substrate was successfully coated with a copper. The growth mechanism of copper layers and surface morphology of PC plastic before and after activated, and surface morphology of PC plastic after electroless plating for different time were analyzed by field emission scanning electron microscopy. The results show that the uniformly copper layers coated with PC substrate is successfully synthesized, which is activated by nitric acid. The dense, uniform distribution copper layers on PC are obtained. The growth mechanism of copper layers appears as follows: reactants in the plating solution are adsorbed on catalytic activity surfaces of PC surface and happened oxidation-reduction reaction. First deposited Cu particles grow in a linear way, the growth process is nano-Cu particle aggregation process, and repeated to form Cu particle physics reunion. Finally, the integration between the Cu particles, and form closely, evenly distributed copper layers. ©, 2014, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.


Lu Z.-L.,Hefei University of Technology | Luo L.-M.,Hefei University of Technology | Luo L.-M.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Huang X.-M.,Hefei University of Technology | And 8 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

Copper (Cu)-coated titanium carbide (TiC) composite powders were synthesized by electroless plating with a simplified pretreatment. The surface morphology and composition of the initial TiC powders, pretreated TiC powders and Cu-coated TiC powders were analyzed by field emission scanning electron microscopy, and energy dispersion spectrometry. The growth mechanism of Cu layers was also discussed. The results show that uniform Cu-coated TiC composite powders are successfully synthesized without conventional sensitization and activation steps by ultrasonic electroless plating after a simple pretreatment. The growth mechanism of Cu layers appears as follows: the surfaces of pretreated TiC powders appear surface defects which act as activated sites. Nucleation and the growth of copper grains take place on the activated sites of the pretreated TiC powder, and the process repeats continuously on the lath particles with reticulate structure on the as-coated surfaces of previously deposited Cu-cells, finally Cu cells grow up and merge into a layer. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.


Luo L.-M.,Hefei University of Technology | Luo L.-M.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Shi J.,Hefei University of Technology | Zan X.,Hefei University of Technology | And 7 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2016

Tungsten matrix composites have gradually replaced the traditional carbon-based materials and beryllium, becoming the most promising candidates for plasma-facing materials for the international thermonuclear experimental reactor attributing to their superior properties. However, tungsten exhibits some problems as a plasma-facing material, including low temperature embrittlement, recrystallization embrittlement, radiation embrittlement and fuel particle retention. Hence, attempts for improving its mechanical behavior have been carried out via doping alloying elements or stable dispersed phases and fabricating UFG/nanocrystalline tungsten, etc. Alloying is one of the most common methods to improve the performance of tungsten-based materials. The doping elements can diffuse and dissolve into tungsten matrix or act on the defects and impurities to change the contexture and structure of tungsten, thus improving its properties. The change of properties and the correlative mechanism of alloyed tungsten-based materials were reviewed and some problems on it and the improvement measures and development trend in future were pointed out. © 2016, Science Press. All right reserved.


Ding X.,Hefei University of Technology | Luo L.,Hefei University of Technology | Luo L.,Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province | Huang L.,Hefei University of Technology | And 5 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2015

With the demand for energy growing rapidly, fossil fuel and other traditional energy resources which bring about serious environmental problems will soon dry up in the foreseeable future. Producing fusion energy by light nuclear fusion reaction is an important potential way to solve the energy problem of human. Recent researches on fusion reactor have made significant progress, and the resulting material problem has become a realistic problem due to that the materials in the reactor will face harsh working environment. Tungsten (W) is considered to be the primary candidate for plasma facing materials like first wall in future fusion reactors owing to its superiority to other materials including high melting point, high thermal conductivity, high density, low thermal expansion coefficient, low vapor pressure, low tritium inventory, low sputtering yield and high energy threshold for physical sputtering, etc. However, there are still serious challenges of brittleness for W and W alloys in the future application for fusion reactors. Defects induced by irradiation often lead to embrittlement of the material, thus shortening the service life of components. The defects will also interact with precious fusion fuel (such as tritium), leading to serious retention and permeation. Therefore, it is very necessary to study the radiation damage of W and W-based materials and it will be of great significance to delay irradiation defects through designing material composition/structure/organization. In order to provide a reference to researchers devoted to irradiation damage, irradiation damage status and the latest research progress of commercial W and advanced W alloys were reviewed in the paper. © Editorial Board of Chinese Journal of Rare Metals. All right reserved.

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