The extraction of scandium from the leaching solution of tungsten residue was carried out by P204-TBP,sulfuric acid eluted the iron in the loaded organic phase and scandium was stripped in the eluted organic phase by sodium hydroxide.The results show that in the system of 5% P204+3% TBP+ kerosene, the extraction rate of scandium is 97.37% through five-stage counter current extraction with O/A ratio of 1∶10,temperature of 25 ℃,and time of 15min.Through five-stage counter current elution by 4 mol/L H2SO4,the elution rate of iron is 98.63%,while the scandium loss rate is less than 1%.The eluted organic phase was stripped with 3mol/L sodium hydroxide.The single-stage stripping rate of scandium reaches 98.31%.By using the method,the purity of crude scandium can reach more than 82%,and the total recovery rate of scandium is more than 95%.

Advanced aliphatic amine extractant are widely used in the metallurgical industry.This paper focuses on several commonly used advanced aliphatic amine extractant and its application in the rare metals solvent extraction process.

TiH2powder with a particle size of less than 74μm and a density of 1.27g/cm^3 was obtained by hydrogenation of pure Ti waste,and then TiH2powder was treated by pretreatment,cold isostatic pressing and high temperature sintering process to produce pure Ti.The strength and density of the compact were tested by three-point bending tester and drainage method.The change trend of the strength and density of the compact,the density of the sintered sample,and the chemical composition and microstructure of the compact were studied by the means of SEM,EDS and the hydrogen/oxygen element analysis.The results show that the TiH2 powder pretreated at 500℃ can obtain higher compact strength and density under the molding pressure of 200MPa.Pure Ti sintered samples with equiaxed structure,density of 4.48g/cm^3 and hydrogen content of 0.001% were prepared from TiH2compacts with vacuum degree higher than 10-3 Pa, calcination temperature of 1400℃,calcination time of 2h.The other chemical compositions of pure Ti sintered samples met the national standard of pure Ti.

The mechanism of synergistic solvent extraction of nickel by P204 and 4PC from acidic sulfate solution was studied with slope method,constant molecale method and saturation extraction method,respectively. The thermodynamic equilibrium constant of the synergistic reaction was determined,and its enthalpy and entropy changes were also obtained.The results show that the combination of P204 with 4PC has a positive synergistic effect for nickel extraction,and the extracted complex is identified as NiA2L2.The synergistic solvent extraction is an endothermic reaction with enthalpy change of 29.52J/mol and entropy change of-6.53kJ/(mol·K).The synergistic solvent extraction system of P204and 4PC can obviously promote the selective extraction of nickel from acidic sulfate solution.

Tungsten-based composite materials were synthesized by using tungsten powder,nickel powder, iron powder and casting wax,and then tungsten-based composite material parts with a certain shape and size were prepared by fused 3D printing forming technique.The appropriate printing parameters were determined and the precision of the printed parts was evaluated.The results show that the viscosity of tungsten- nickel-iron-paraffin composite material with 85% solid content is stable with temperature changing, which can maintain the stability and fluidity of the material inside the printing cavity,and obtain a higher solid content of the part at the same time.The composites with the solid contents of 80%,85% and 88% have a uniform density distribution inside the cavity,and their melt has certain stability and uniformity inside the printing cavity.The appropriate printing parameters are as follows:printing temperature of 130~ 132℃,supply pressure of 124.11~151.69kPa,printing ring distance of 1.1mm,and layer height of 1.24 mm.The precision of the parts printed with the above method is low,which is mainly affected by the discharge mode and program control.

The 90W-Ni-Fe alloy parts were fabricated by 3D cold printing using military-grade tungsten powder,nickel powder and iron power as the raw materials.The effects of binder and solid contents on the viscosity of metal slurry were studied,and the microstructure uniformity of the green body was also investigated. The debinding and sintering process was optimized according to TG-DTA curves,and the morphology, metallographic microstructure and density of the sintered body were analyzed.The results show that the W-Ni-Fe metal slurry with 4% binder and 70%~75% solid is the most suitable for 3D cold printing. The microstructure of the green body is uniform in the vertical direction,the metal particles are uniformly filled in the three-dimensional network structure composed of PVB,and solid particles are uniformly distributed without obvious settlement.In the printing process,the thickness of the green body nonlinearly grows,the width is unstable,and therefore the curing rate of the slurry still needs to be improved.After the green body was degreased and sintered at 1440℃ for 2h,the sintered body with 16.26g/cm^3 density is obtained,and its relative density is as high as 94.83%.

Mo-Cu plates were prepared by tape-casting technique,combined with debinding-sintering process.Then the Mo-Cu ultrathin sheets were acquired by rolling and annealing.The X-ray diffraction (XRD),carbon sulphur analyzer,metallographic microscope,density gauge and microhardness tester were used to characterize the phase,composition,microstructure and the Vickers hardness of Mo-Cu ultrathin sheet at different conditions.XRD analysis shows that only the characteristic diffraction peaks of Mo and Cu were found in Mo-Cu ultrathin sheets,and no new phase was formed.The carbon sulphur analysis shows that the sheets debinding completely,only with the carbon content of 0.01809%.The relative density and the Vickers hardness of the Mo-Cu ultralthin sheet were 98.42%and 266,respectively,which were improved by rolling-annealing technique.

The effect was studied of heat treatment temperature on microstructure of Ti-42.5Al-4Nb-1Mo-0.2 Balloy for internal combustion engine.The results show that the alloy has nearly lamellar microstructure in the as-cast state,mainly composed of fine lamellar clusters and B2 phase andγphase around the lamellar clusters.The quenched alloys at 1200℃ and 1250℃ have similar microstructure.With the quenching temperature is increased to 1300℃,γphase in quenched microstructure disappears,and there are some long rod-shaped fine α2 grains in B2 grains.After heat treatment at 1200℃ and cooling to room temperature, the alloy has the microstructure of α2/γ lamellar clusters,B2 phase andγphase.When the heat treatment temperature is up to 1250℃,the number ofαgrains and α2/γ lamellar clusters begins to increase, and their size also gradually increases.When the heat treatment temperature rises to 1300℃,the alloy has nearly lamellar fine α+β microstructure.

The effects were investigated of Ta and Zr contents on the microstructure and damping properties of theβ-type titanium alloy Ti-36 Nb-xTa-yZr-0.3 Oby metallographic analysis and dynamic thermomechanical analysis(DMA).The results show that Ta and Zr addition has no effect on the grain size of the alloy.Ta addition results in the dipole shape factor of the alloy increased and the damping value improved,but the relaxation activation energy and the critical temperature almost have no change and therefore the peak temperature and the peak width have no significant change.The addition of Zr has little effect on the dipole shape factor of the alloy,and the damping value is basically unchanged,but the relaxation activation energy and the critical temperature increase,leading to increased peak temperature and peak width.

The thermal compression tests of Ti-B25 alloy were conducted on Gleeble 3800 thermal simulator under the conditions of 800~1000℃ temperature,0.01~10s^-1 strain rate and 70% strain.The results show that in the initial deformation stage of Ti-B25 alloy,the flow stress increases rapidly with the increase of strain.However,after reaching the peak value,the flow stress begins to decrease and gradually stabilizes, showing a steady flow characteristic.During high temperature deformation,both steady stress and peak stress decrease significantly with the increase of temperature and the decrease of strain rate.Through regression processing of the data,the functional relationships are fitted between the thermal deformation activation energy Q,the structural factor A,the stress index nor the stress level parameterαand the strainε, and then the constitutive equation of the alloy during high temperature deformation is obtained.