WCoB-TiC cermets were prepared by the spark plasma sintering process.The effects of SPS temperature on the microstructure and mechanical properties of WCoB-TiC were investigated.The experimental results show that the density and hardness of the cermets firstly increase and then decrease with the increase of sintering temperature.When the sintering temperature is 1300℃,the microstructure compactness of the WCoB-TiC cermet is the best,the density reaches 9.33g/cm³,and the hardness and bending strength are the highest,which are 92HRA and 824MPa,respectively.When the sintering temperature is increased from 1100°C to 1300°C,the fracture mode of the cermets gradually changes from cleavage fracture to quasi-cleavage fracture.When the sintering temperature reaches 1400℃,the grain growth leads to the decline of various mechanical properties of the cermet.

In order to improve the mechanical properties of Ni-based plasma cladding layer, single crystal WC powder was added into the Ni-based powder.The influence of adding different amounts of WC on the microstructure and mechanical properties of Ni-based plasma cladding layer was studied by SEM analysis, hardness test, wear resistance test and other methods.The results show that when 0~30% WC is added into Ni60 alloy powder, with WC addition amount increasing, the macroscopic morphology of Ni-based plasma cladding layer gradually deteriorates, and undecomposed WC particles gather more and more at the fusion line, while the surface hardness of the cladding layer shows an increasing trend, and the wear resistance is gradually improved.In actual production, it is necessary to comprehensively consider the macro-morpho-logy and property requirements of Ni-based cladding layer before reasonably determining WC addition amount.

Taking hot-pressed sintered tungsten carbide(WC)and gas carburized WC coatings as the re-search objects,their microstructure,element composition,crystal orientation,phase composition and distri-bution were characterized by in-situ SEM,EDS,EBSD,XRD and Raman spectrometer.The analysis results show that the coating cross-section contains WC,W₂C and amorphous phase.The grain size of WC main phase is about 3μm,the thickness is about 15μm,and it is hexagonal and polycrystalline.The main peak positions in Raman spectrum of WC layer are consistent with the characteristic peak positions of WC(A₁110cm^-1 and A₂166cm^-1),and the peak shape and position are consistent with those of sintered WC.WC grains grow along(101)crystal plane,showing apreferential orientation and resulting in increased intensi-ty of 75cm^-1 Raman peak,which is consistent with XRD results.The crystal structure of W₂C is hexago-nal,and there are two kinds of W₂C microstructures in the coating:Fine grains of uniform distribution are near the surface layer and the abnormally grown single crystals are near the substrate.The main Raman peak positions of W₂C area are consistent with W₂C characteristic peak positions(E_g128.5cm^-1 and A_1g 220cm^-1),and they have no interference with WC main peaks.The amorphous layer with a width of about 2μm is located between the W₂C fine-grained area and the substrate,and it contains about 2%(molar frac-tion)Fe impurity.Raman spectrum of the amorphous layer shows peakless bulge,which is well distin-guished from other phases.Raman spectrum analysis of the coating verifies the phase distribution results obtained by EBSD,and the phase composition information of the coating material cross-section is enriched.Due to the complexity of EBSD sample preparation,Raman spectrum has an irreplaceable advantage in the rapid identification of WC,W₂C and amorphous phase.

In order to improve the properties of molybdenum wire,using ammonium tetramolybdate,nitric acid,aluminum nitrate and urea as raw materials,MoO₃-Al₂O₃ precursor was prepared by hydrothermal method,and then Mo-Al₂O₃ composite powder was obtained by low temperature calcination and two-stage hydrogen reduction.Then,the Mo-Al₂O₃ molybdenum rod with a diameter of about 20mm was obtained by pressing and high temperature sintering,and finally the Mo-Al₂O₃ molybdenum wire with a diameter of 0.18mm was obtained by blanking,rotary forging,drawing,annealing and cold drawing.The effects of different Al₂O₃ doping contents on the microstructure and properties of molybdenum powder and molybde-num wire were studied,and the strengthening mechanism of molybdenum wire was analyzed.The results show that the addition of Al₂O₃ particles can refine Mo grains and improve the properties of molybdenum wire.The more the addition amount of Al₂O₃ particles,the greater the grain refinement degree of Mo-Al₂O₃,and the better the mechanical properties of molybdenum wire.The strengthening mechanism of Al₂O₃-doped molybdenum wire is dispersion strengthening,grain refinement strengthening,work harden-ing and texture strengthening,which together endow the Al₂O₃-doped molybdenum wire with ultra-high strength.Within the experimental range,the tensile strength and elongation of Mo-0.25%Al₂O₃are the highest,reaching 2243MPa and 3.9%,respectively.

In view of the excellent comprehensive properties of Al-Cu alloys,the research progress of the effects of Sc and the combined addition of Sc and other elements in Al-Cu alloys at home and abroad is re-viewed,which include the changes of grain size,phase composition and distribution,physical and mechani-cal properties of Al-Cu alloys after the addition of Sc or the combined addition of Sc and other elements.The matters needing attention and the contents needing further study in future research are analyzed and discussed.

Different amounts of Pr₈₃Cu₁₇ alloy powder were added into grain boundary of RE-Fe-B magnets with high La-Ce content(40%of RE mass),and the effect of Pr₈₃Cu₁₇ alloy on the magnetic properties and microstructure of the magnets was systematically studied.The results show that intergranular Pr₈₃Cu₁₇ alloy can effectively improve the microstructure of the La-Ce-containing magnets,and the rare earth-rich grain boundary phase distribution becomes clear and continuous.At the same time,the Pr element diffuses into the main phase grain edge to form a core-shell structure,which effectively improves magnet coercivity.When Pr₈₃Cu₁₇ alloy addition is 5%,10%and 15%of the magnet mass,the coercivity of the magnet is in-creased by 60%,119%and 166%,respectively.When Pr₈₃Cu₁₇ alloy addition is 5%of the magnet mass,the remanence of the magnet is 12.18kGs,the coercivity is 6.205kOe,and the maximum magnetic energy product is 31.01MGOe.Due to the high content of La-Ce in the magnet,the use of La and Ce elements in rare earth magnetic materials can be effectively promoted to achieve the purpose of efficient and balanced utilization of rare earth resources.

The lithium-rich manganese-based oxide(LMO)shows high specific capacity,but it still has some defects,such as large initial irreversible capacity loss,poor dynamic performance and voltage decline.In this paper,the structure of Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ cathode material was designed and optimized.The transfer of lattice oxygen in charge-discharge cycle is limited by doping Br^- to substitute O^2-.The reversibility of oxygen anion reaction is enhanced by adjusting oxygen vacancy in LMO electrode,and the cycle stability of the electrode is also improved.The substitution of the non-equivalent Br^- is more likely to pro-duce oxygen vacancy,thereby increasing the conductivity of the material,improving the Li⁺diffusion kine-tics,and enhancing the rate performance of the material.

By studying the effect of different current density on the preparation of reference electrode by electroplating, a step current electroplating method was proposed.The experimental results show that the reference electrode prepared with low current density has stable potential, but it is easy to fall off, the re-ference electrode prepared with high current density has firm combination but poor potential stability, and the reference electrode prepared by step current method has better stability and accuracy.The li-thium evolution potential of the negative electrode charged at different charging rates was explored by using the optimized reference electrode.The results show that the greater the charging rate, the easier the lithium evolution of the negative electrode.The lithium evolution potential boundary of the negative electrode is from-20 mV to-110 mV at 10 ℃.

Magnesium batteries not only have the advantages of high efficiency and high energy density, but also they are economical, safe and environmentally friendly, expected to become a new generation of chemical power source beyond lithium batteries.The advantages, application field and latest research results of various types of magnesium batteries are reviewed, including magnesium-seawater batteries, magnesium-air batteries(magnesium metal fuel cells),magnesium primary batteries and rechargeable magnesium batte-ries(magnesium ion batteries).

Single crystal APT and polycrystalline APT prepared by different crystallization processes were used as raw materials to produce single crystal tungsten trioxide and polycrystalline tungsten trioxide after high temperature calcination.Then, using single crystal tungsten trioxide and polycrystal tungsten trioxide as raw materials, medium grain tungsten powder, tungsten carbide and WC-6%Co cemented carbide were prepared, and the effect of APT morphology on the microstructure, physical and mechanical properties of powder products and cemented carbide were studied in detail.The results show that the tungsten trioxide prepared by calcining APT with different morphologies still retains the morphology of APT.The tungsten powder prepared by two kinds of tungsten trioxide with different morphologies is quasi-spherical, but the tungsten powder prepared by single crystal tungsten trioxide has good uniformity, less fine powder, no obvious crystallographic plane and high spheroidization degree.However, the tungsten powder prepared by polycrystalline tungsten trioxide has poor uniformity, more fine powder and obvious crystallographic plane.In the carbonization process, the grain size of tungsten powder prepared by single crystal tungsten trioxide increases by 21.5%,which is significantly higher compared with tungsten powder prepared by polycrystalline tungsten trioxide, and the granules with high spheroidization degree are more in the prepared tungsten carbide.Compared with WC-6%Co cemented carbide prepared by polycrystalline APT,WC-6%Co cemented carbide prepared by single crystal APT has higher coercive force, hardness and bending strength, better microstructure uniformity and more excellent overall properties.