《稀有金属与硬质合金》是一本公开发行的、致力于稀有金属冶金与材料领域的学术期刊,自1973年创刊以来,始终秉承“传播先进科技成果,引领创新,贴近科研与生产”的办刊宗旨,为广大科研人员、工程技术人员提供可靠、详实的参考文献。

《稀有金属与硬质合金》由中国有色金属学会和长沙有色冶金设计研究院有限公司联合主办,长沙有色冶金设计研究院有限公司负责编辑出版,为2023版北大中文核心期刊、中国科学引文数据库来源期刊,入编《中国学术期刊(光盘版)》和《中国科技期刊数据库》等数字化网络。《稀有金属与硬质合金》现为双月刊,公开发行,国际标准连续出版物号:ISSN 1004-0536,国内统一连续出版物号:CN 43-1109/TF。本刊主要报道稀有金属/半金属(钨、钼、稀土、钽、铌、钒、钛、锆、铪、铍、锂、铷、铯、镓、铟、铊、锗、硒、碲、铼等)和硬质合金的生产、加工、科研、设计及应用成果;报道国内外稀有金属与硬质合金的新工艺、新技术、新设备和新材料等方面的文章及信息。

Using ultrafine-grained WC-6Co-0.7Cr₃C₂-0.4VC cemented carbide as the research object,six groups of mixed powders with different carbon additions(mass fraction)were blended,and then cemented carbide samples with different carbon contents were fabricated via pressing and sintering.The effects of carbon addition on the microstructure and physical-mechanical properties of the cemented carbide were analyzed using metallographic microscope,scanning electron microscope(SEM),magnetic saturation tester,coercivity meter,water displacement method,Vickers hardness tester,and mechanical testing machine.The results show that the cemented carbides with carbon additions of 5.74%and 5.78%are in the WC+Co two-phase region.When the carbon addition is below 5.74%,the decarburization phase(ηphase)appears in the substrate.When the carbon addition exceeds 5.78%,the snowflake-like carburization phase(C phase)forms.As carbon addition increases,the relative saturation magnetization of the cemented carbide initially rise gradually and then slightly decreases,while coercivity and density generally decline.The Vic-kers hardness progressively decreases,the fracture toughness initially increases,then decreases,and finally slightly recovers,and the transverse rupture strength(TRS)rises sharply before gradually declining.When the carbon addition is controlled within the range of 5.74%to 5.78%,the cemented carbide remains in the WC+Co two-phase region,achieving an optimal balance of hardness,strength,and toughness.The fracture surface of the cemented carbide with a carbon addition of 5.66%exhibits dotted decarburization phase,which acts as fracture origins and reduces the strength and toughness of the cemented carbide.In contrast,the fracture surface of the two-phase cemented carbide with a carbon addition of 5.74%exhibits a uniform microstructure without defects.However,the fracture surface of the cemented carbide with a carbon addition of 5.86%contains black carburization phase,which degrades the strength,hardness,and toughness of the cemented carbide.

GH3539 alloy ingots with different W contents(26%,30%,and 35%by mass)and Ti contents(0,0.5%,and 1.2%by mass)were prepared in a vacuum induction melting furnace and subjected to ho-mogenization heat treatment.The microstructure of the alloy was characterized using scanning electron microscope(SEM),energy dispersive spectrometer(EDS),electron probe microanalyzer(EPMA)and electron backscatter diffraction technique(EBSD).The influence of Ti and W elements on the hot deformation behavior of GH3539 alloy was studied by isothermal compression tests at a temperature of 1200℃,strain rates of 0.01~1 s^-1,and a strain of 50%.The results indicate that as the content of Ti and W increases in the GH3539 alloy,the number of granular precipitates in theγmatrix of the alloy also increases gradually.Increasing the content of Ti element raises the volume fraction of Ti-rich MC carbides in the alloy,significantly reducing the deformation resistance and markedly improving the hot workability of the alloy.Additionally,the addition of Ti also reduces the recrystallized grain size of the hot-deformed alloy and increases its recrystallization volume fraction.Increasing the content of W element promotes the precipitation of M₆C carbides andα-W particle phase.When 35%W is added,a large number of blockyα-W phase wrapped by M₆C carbides precipitates in the homogenized heat-treated alloy.Although this W-rich particulate phase promotes the dynamic recrystallization of the matrix to a certain extent,it also readily becomes crack sources during high-temperature deformation,thus deteriorating the hot workability of the alloy.

TZM alloys were prepared by doping TiH₂+ZrH₂,TiC+ZrC and TiC+ZrC+HfC,respectively,and the microstructure and mechanical properties of the alloys prepared by different sintering and vacuum hot pressing processes.The results indicate that the density of the alloys can be improved by changing the form of Ti and Zr addition and adding HfC.Compared with the addition of TiH₂+ZrH₂,the density of the alloys prepared by adding TiC+ZrC and TiC+ZrC+HfC increases from 9.51 g/cm³ to 9.71 g/cm³ and 9.81 g/cm³,respectively.The relative density of the alloys with different ingredients is significantly improved when hot pressing is carried out after sintering,in which maintaining pressure after pressurization is more effective in increasing the relative density of the alloys.The original ingredients with different doping methods undergo decomposition and diffusion during the sintering process of the alloys,forming Mo solid solution phase.In comparison with the addition of TiH₂+ZrH₂,the alloys prepared by adding TiC+ZrC and TiC+ZrC+HfC have smaller grains,and the added TiC,ZrC and HfC particles can achieve grain refinement through dissolution and precipitation.Adding HfC beyond TiC+ZrC can increase the yield strength of the alloy prepared by the same process from 314 MPa to 390 MPa,with an improvement of about 24%.HfC is beneficial for the purification of grain boundaries and the refinement of Mo matrix grains,thereby improving the strength of molybdenum alloy.

(Ti_42.5Zr_42.5Nb₁₀Ta₅)₉₃Mo₇ refractory high-entropy alloy ingots were prepared using a non-consumable vacuum arc melting furnace.A systematic study was conducted on the effects of 0.05%(mole fraction)carbon doping on the microstructure,mechanical properties and tribological properties over a wide temperature range of the alloy using X-ray diffractometer(XRD),scanning electron microscope(SEM),energy-dispersive spectrometer(EDS),electron backscatter diffractometer(EBSD),electron probe microanalyzer(EPMA),X-ray photoelectron spectrometer(XPS),microhardness tester,room-temperature tensile testing,and high-temperature friction and wear testing.The results show that both the undoped and 0.05%C-doped alloys are composed of a single BCC phase,and trace carbon doping does not lead to the formation of a second phase.Due to the grain boundary segregation effect,trace carbon doping increases the hardness of the alloy from 337.3 HV_0.2to 357.6 HV_0.2,the fracture strength from 693 MPa to 1040 MPa,and the elongation from 1.11%to 25.79%.The wear resistance of the two alloys initially decreases,then increases,and finally decreases again with the rise in test temperature.The wear mechanism transitions from predominant abrasive wear at room temperature to predominant oxidative wear at high temperature(700℃).At different test temperatures,the 0.05%C-doped alloy consistently exhibits better wear resis-tance.

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In order to separate Sc and impurity ions from titanium white waste acid,the extraction and separation behaviors of Sc,Ti,Fe and Al from titanium white waste acid by N503-P204 and TBP-P204 synergistic extraction systems were studied.The results show that the Sc extraction rates in the systems of 5%N503+5%P204+90%sulfonated kerosene and 5%TBP+5%P204+90%sulfonated kerosene are 99.74%and 99.73%,respectively by two-stage countercurrent extraction under the conditions of 25℃and O/A=1∶20.In the N503-P204 synergistic extraction system,99.34%Ti is eluted with 1 mol/L phosphoric acid through two-stage countercurrent washing under the conditions of 35℃and O/A=1∶2,while only 66.22%Ti is eluted in TBP-P204 synergistic extraction system under the same conditions.Combined with infrared characterization,it is confirmed that the extraction and separation efficiency of N503-P204 synergistic extraction system on Sc is superior to that of TBP-P204 synergistic extraction system.In N503-P204 synergistic extraction system,when 2 mol/L sodium hydroxide is used for stripping under the conditions of 50℃and O/A=3∶1,Sc stripping rate reaches 99.28%,while Fe,Al and other impurities are left in the organic phase,realizing Sc recovery.

By thermodynamic calculation using Miedema mixing enthalpy model,the saturated vapor pressure of each element in scandium metal,the separation coefficient of impurity elements from Sc,and the distillation volatilization rate were obtained.The separation characteristics and rules of Fe and Al impurities in the process of scandium metal purification by vacuum distillation were analyzed.According to the results of theoretical analysis,the vacuum distillation and purification experiment of scandium metal was carried out under the conditions of distillation temperature of 1550~1700℃and vacuum degree less than 10^-3Pa.The calculation results show that the saturated vapor pressure difference between the impurities Mg,Ca,Mn,and Ni and the main element Sc is large,and they are easy to separate by vacuum distillation,while Fe and Al impurities with saturated vapor pressure close to Sc are difficult to separate.The separation coefficient of Al and Fe impurities from Sc at 1550~1700℃is far less than 1 and gradually increases with the increase of distillation temperature,which is not conducive to the separation of Sc from Fe and Al.With the increase of distillation temperature,the volatilization rate of Sc and impurity Fe and Al gradually increases,and the volatilization rate of the impurities further increases with the increase of their content.The experimental results show that vacuum distillation can effectively remove Fe and Al impurities in scandium metal,so that they remain in the slag phase.