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Selective leaching of calcium from mechanically activated mixed rare earth concentrate

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Journal of Rare Earths 2024年第6期42卷 1149-1156,I0006页

作者： Jiang Liu Bingxue Chen Yuanqi Feng Yijun Cao Yukun Huang Yuan Shi Meng Li Zhongyuan Critical metals Laboratory School of Chemical EngineeringZhengzhou UniversityZhengzhou450001China State Key Laboratory of Advanced Processing and Recycling of Nonferrous metals Lanzhou University of TechnologyLanzhou730050China

The loss of rare earths(REs)takes place during the pre-decalcification process of mixed rare earth *** an effort to reduce such RE loss,a novel idea to improve the leaching selectivity of Ca to REs by applying selective mechanical activation was ***,regarding the key minerals affecting the leaching selectivity of Ca to REs,the differences in the mechanical activation behaviors of CaF_(2) and REFCO_(3) were studied,and we find that the lattice strain of CaF_(2) increases from 0.21%to 0.42%,whereas that of REFCO_(3) increases from 0.31%to 0.40%.Notably,CaF_(2) demonstrates a larger lattice strain than REFCO_(3),indicating greater mechanical activation energy storage and higher leaching ***,the HCl leaching process was studied.A significant leaching selectivity of Ca to REs,from 21.6 to 35.1,is achieved through mechanical *** Ca leaching rate reaches 80.7%when the RE loss is 2.3%in the activated *** study provides an novel approach for achieving selective extraction of specific components via mechanical activation pretreatment.

关键词： Mixed rare earth concentrate Pre-decalcification Selective mechanical activation Selective leaching

Preparation and characterization of Rb-doped TiO_(2) powders for photocatalytic applications

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Rare metals 2024年第2期43卷 555-561页

作者： Lu Jia Li-Mei Yang Wei Wang Song-Tao Huang Zheng Xu National Engineering Laboratory of Biohydrometallurgy General Research Institute for Nonferrous MetalsBeijing100088China

TiO_(2)nanoparticles doped with different concentrations of Rb were prepared by sol–gel *** crystal structures of samples were characterized by X-ray diffraction(XRD)and transmission electron microscopy(TEM).It was confirmed by the Rietveld refinement method that the as-prepared samples crystallize in anatase phase and Rb doping induces expansion and distortion of the crystal *** with the pure TiO_(2),the Rb-doped nanoparticles have smaller crystal size and better *** rate of methylene blue was used to evaluate the photocatalytic activity of Rb–TiO_(2).It indicated that doping Rb into TiO_(2)can effectively improve the photocatalytic activity of TiO_(2)and the mechanisms were discussed in *** using the sample doped with 0.20%Rb,methylene blue degraded with the fastest rate(97%within 60 min).

关键词： Rb doping TiO_(2) Photocatalysis Sol-gel

Precipitation evolution and properties of Cu-15Ni-8Sn alloys via Al microalloying during ageing

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Rare metals 2024年第10期43卷 5216-5228页

作者： Wei Luo Li-Jun Peng Xu-Jun Mi Hao-Feng Xie Yi-Cheng Cao Shu-Hui Huang State Key Laboratory of Nonferrous metals and Processes GRINM Group Co.Ltd. GRIMAT Engineering Institute Co. Ltd. General Research Institute for Nonferrous metals School of Materials Science and Engineering South China University of Technology

Studies have shown that microalloying Cu-Ni-Sn alloys using Al inhibits discontinuous precipitation reactions;however,the mechanism has not been investigated ***,this study explored the properties and precipitation evolution of Cu-15Ni-8Sn alloys without and with 1 wt%Al（Cu-15Ni-8Sn-1Al） during ageing at 500℃ through X-ray diffraction （XRD）,scanning electron microscopy and high-angle annular dark-field scanning transmission electron *** results revealed that in Cu-15Ni-8Sn alloy,DO22ordering first occurred after spinodal decomposition,subsequently transitioning to an L12ordering phase,during which the discontinuous precipitates gradually nucleated at the grain boundaries and formed *** alloy hardness increased sharply with ordering and then decreased rapidly after reaching its peak value,due to the dominance of the discontinuous precipitation ***,the DO22ordered phase did not appear during the ageing of Cu-15Ni-8Sn-1Al alloy,and a Ni3(Alx,Sn1-x) intermetallic compound with L12structure was formed,consuming Ni and Sn atoms,thereby significantly suppressing the discontinuous precipitation reaction and improving the stability during prolonged *** tensile strength （yield strength） of Cu-15Ni-8Sn and Cu-15Ni-8Sn-1Al alloys at peak hardness were 855 （755） and 936 MPa （892 MPa）,respectively,and their main strengthening mechanisms were solid solution strengthening and precipitation *** addition of 1 wt% Al effectively improved the precipitation strengthening effect of Cu-Ni-Sn alloys but severely decreased the ductility.

关键词： Al addition Cu-15Ni-8Sn Precipitation sequence Strengthening mechanism

Microstructure and properties of coarse-grained WC-10Co cemented carbides with different carbon contents during heat treatments

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Rare metals 2024年第4期43卷 1786-1792页

作者： Yuan-Feng Xie Xing-Cheng Xie Zhong-Wu Li Rui-Jun Cao Zhong-Kun Lin Qing Li Chen-Guang Lin Powder Metallurgy and Special Materials Research Department General Research Institute for Nonferrous MetalsBeijing100088China

The effects of cryogenic treatment(CT)and tempering-cryogenic treatment(TCT)on the microstructure and properties of coarse-grained WC-10Co cemented carbides with different carbon contents were *** binder phase,WC mean grain sizes,W solubility in the binder,relative magnetic s aturation,densities,hardness,wear resistance and second phase precipitation of cemented carbides with different heat treatments were *** results show that there are significant changes of microstructure and properties in the samples with CT and TCT,especially due to the precipitation of metastable nanoparticles W_(x)Co_(y)C_(z) in the binder during the heat treatments of CT and *** the simultaneous combination of microstructure and nanoparticle-reinforced binder,a dramatically improved combination of hardness and wear resistance of the samples after TCT has been achieved.

关键词： Cryogenic treatment Tempering Coarsegrained cemented carbide Carbon content Nanoparticlereinforced binder

Hot Deformation Behavior of Ti-6Al-4V-0.5Ni-0.5Nb Titanium Alloy

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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1270-1277页

作者： ZHU Guochuan LIU Qiang SONG Shengyin HUI Songxiao YU Yang YE Wenjun QI Jun TANG Zhengwei XU Penghai CNPC Tubular Goods Research Institute Xi’an 710077China State Key Laboratory for Fabrication&Processing of Nonferrous metals Beijing General Research Institute for Nonferrous MetalsBeijing 100088China China Petroleum Tarim Oilfield Company Korla 841000China

Characterization of hot deformation behavior of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy was investigated through isothermal compression at various temperatures from 750 to 1050℃and strain rate from 0.01 to 10 s^(-1).The isothermal compression experiment results showed that the peak stress of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy decreased with the temperature increasing and the strain rate *** softening mechanism was dynamic recovery below T_(β)and changed to dynamic recrystallization above T_(β).The arrheniustype relationship was used to calculate the constitutive equation of Ti-6Al-4V-0.5Ni-0.5Nb alloy in two-phase *** was found that the apparent activation energies were 427.095 kJ·mol^(-1)in theα+βphase region and 205.451 kJ·mol^(-1)in theβphase region,*** the basis of dynamic materials model,the processing map is generated,which shows that the highest peak efficiency of power dissipation of 56%occurs at about 1050℃/0.01 s^(-1).It can be found in the processing maps that the strain had significant effect on the peak region of power dissipation efficiency of Ti-6Al-4V-0.5Ni-0.5Nb ***,optimized hot working regions were investigated and validated through microstructure *** optimum thermo mechanical process condition for hot working of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy was suggested to be in the temperature range of 950-1000℃with a strain rate of 0.01-0.1 s^(-1).

关键词： titanium alloy hot deformation processing map dynamic recrystallization

Experimental and DFT Investigations of AlNbTiVZr High Entropy Alloys with Excellent Mechanical Properties

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1480-1490页

作者： Hongwei Yan Yong'an Zhang Wei Xiao Boyu Xue Rui Liu Xiwu Li Zhihui Li Baiqing Xiong State Key Laboratory of Nonferrous metals and Processes China GRINM Group Co.Ltd.Beijing100088China GRIMAT Engineering Institute Co. Ltd.Beijing101407China General Research Institute for Nonferrous metals Beijing100088China

This study investigated the microstructure and mechanical properties of AlNbTiVZr series high-entropy alloys(HEAs)through both experimental studies and density functional theory *** improvements in the microstructures and mechanical properties were achieved for the AlNbTiVZr series HEAs by meticulously adjusting the alloy composition and employing homogenization heat ***,the specimen designated as Al_(0.5)NbTiVZr_(0.5) demonstrated excellent mechanical properties including a compressive yield strength of 1162 MPa and a compressive strength of 1783 *** homogenization heat treatment at 1000℃ for 24 h,the Al_(0.5)NbTiVZr_(0.5) alloy exhibits brittle-to-ductile *** atomic-scale theoretical simulations reveal that the decrease of Al content intrinsically enhances the ductility of the alloys,thereby indicating that the mechanical properties of the AlNbTiVZr series HEAs were significantly influenced by the chemical ***,specific atomic pair formations were observed to adversely affect the microstructure of the AlNbTiVZr series HEAs,particularly in terms of *** findings provide valuable insights for the design and optimization of light weight HEAs,emphasizing the synergistic adjustment of alloy composition and heat treatment processes to achieve a balance between the strength and ductility.

关键词： High-entropy alloy Microstructure Mechanical properties Density functional theory

Dielectric and energy storage properties of PbO–SrO–Nb_(2)O_(5)–Na_(2)O–Si thin films by annealing

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Rare metals 2024年第1期43卷 351-355页

作者： Fei-Hu Tan Qing-Meng Zhang Feng Wei Hong-Bin Zhao Xiao Zhang Jun Du State Key Laboratory of Advanced Materials for Smart Sensing General Research Institute for Nonferrous MetalsBeijing 100088China Advanced Electronic Materials Institute General Research Institute for Nonferrous MetalsBeijing 100088China

Dielectric and energy storage properties of PbOSrO-Na_(2)O-Nb_(2)O_(5)-SiO_(2)(PSNNS) thin films with annealing temperature from 700 to 850 ℃ were investigated by measuring their capacitance-electric filed curve and hysteresis *** results show that the highest dielectric constant and energy density are 81.2 and 17.0 J·cm^(-3),respectively,which is obtained in the sample with annealing temperature of 800 ℃.Annealed from 700 to800 ℃,the dielectric constant and energy storage performance of PSNNS films are continuously ***,with annealing temperature up to 850 ℃,their dielectric constant decreases,which might be related with the removal of interfacial defects as a function of annealing *** is one of the causes of space charge phenomenon,resulting in the increase in dielectric ***,the micro structure analysis by X-ray diffraction(XRD) and transmission electron microscope(TEM) indicates that the change of crystallization phase and interfacial polarization takes responsibility to the results.

关键词： Thin film Pulse laser deposition Annealing temperature Energy storage density

A novel molybdenite depressant for efficient selective flotation separation of chalcopyrite and molybdenite

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International Journal of Mining Science and Technology 2024年第8期34卷 1179-1196页

作者： Mengyao Qi Weijun Peng Wei Wang Yijun Cao Longyu Zhang Yukun Huang School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China Zhongyuan Critical metals Laboratory Zhengzhou UniversityZhengzhou 450001China The Key Lab of Critical metals Minerals Supernormal Enrichment and Extraction Ministry of EducationZhengzhou 450001China

A novel small molecule depressant(M-DEP)was used to separate chalcopyrite and molybdenite via *** results showed that M-DEP had an excellent selective depression on molybdenite,while had little effect on the flotation of *** adsorption capacity of M-DEP on the surface of molybdenite was greater than that on chalcopyrite *** adsorption of M-DEP reduced the floatability of molybdenite and had less effect on the floatability of chalcopyrite,which was due to its different adsorption modes on the surface of the two ***,the interaction between chalcopyrite and M-DEP was mainly chemical interaction,and almost all of the adsorbed M-DEP molecules were removed and replaced by sodium butyl xanthate(SBX).By contrast,hydrophobic interaction was the main way in which M-DEP was adsorbed on the molybdenite surface with little chemical interaction,which was less interfered by SBX ***,M-DEP had a super selective depression on *** study provided a novel depressant and approach for the deep separation of chalcopyrite and molybdenite via flotation.

关键词： Novel molecule depressant Molybdenite Chalcopyrite Flotation separation Selective depression

Diversification of interfaces triggered hydrogen storage properties enhancement

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Rare metals 2024年第5期43卷 2324-2330页

作者： Jia-Xin Zhang Xin Ding Rui-Run Chen Xiang-Feng Ma Wen-Chao Cao Yong Zhang Jing-Jie Guo National Key Laboratory for Precision Hot Processing of metals Harbin Institute of TechnologyHarbin 150001China

Dual effects of grain refinement and alloying are achieved and the mechanism of"diverse interfaces reinforcement"for hydrogen storage Mg alloys is first *** interface reinforced Mg-Y-Zn-Al alloy for hydrogen storage is *** work figures out that the adventurous Al-rich phase exhibits an ordered face-centered cubic(FCC)structure with composition of(31±2)at%Y-(28±1)at%Zn-(41±3)at%Al,i.e.,Y_(3)Zn_(3)Al_(4),and an incoherent interface between Y3Zn3Al4phase and Mg substrate is observed.

关键词： hydrogen alloying alloy