The four light rare earth elements of La, Ce, Pr and Nd were extracted by fuzzy linkage extraction technology from Baotou mixed rare earth ore. Compared with the traditional process, fuzzy linkage extraction technology is a separation process for light rare earth with obvious energy conservation and emission reduction effects. The new technology has the advantages of less investment in infrastructure and good extraction separation efficiency. Its acid and alkali consumption can be reduced by about 20 %,and its unit discharge of waste water is only 79.4% of that of the traditional technology.

Investigation is made on the amount of the residual elements by ICP-AES and ICP-MS during va- nadium extraction from direct acid leaching solution of carbonaceous shale vanadium ore. During alkali addition for impurity removal,vanadium retention rate is high at pH of 2.8 and 12.2,and element retention rate-pH curves are divided into four groups： U-type curves, descending curves, ascending curves and horizontal curves. During oxidation,four kinds of oxidants were added into the solution with the pH of 2.8 and 12.2. In terms of oxidation effect and production cost,the use of Na2S2O8 with pH of 2.8 can result in optimal oxidization effect. Extraction-stripping cannot remove Na impurity of the highest content, but it can greatly increase the content of P impurity instead. The necessity of extraction-stripping is to be further studied

Research is done on the catalytic oxidation and hydrochloric acid leaching of nickel and cobalt from nickel concentrate under normal pressure with oxygen and copper chloride as oxidizing agent and catalytic agent, respectively. The influences were investigated of leaching temperature, leaching acidity, oxidation-reduction potential, particle size of nickel concentrate and catalytic agent concentration on nickel and cobalt leaching rate. The optimal technical parameters of hydrochloric acid catalytic oxidation leaching were determined by experimental study. The leaching rate of nickel and cobalt can reach 98. 16% and 93.32% respectively under the conditions as follows：leaching duration of 180 min,leaching temperature of 90℃ ,final potential of leaching solution of 520 mV, nickel concentrate particle size less than 0. 075 mm, stirring speed of 600 r/min,liquid-solid ratio of 4 ： 1,leaching acidity of 2 mol/L,Cu2＋ concentration of 25 g/L, NaCl concentration of 100 g/L,and oxygen flow rate of 0.5-0.6 L/min.

Porous tungsten blank with continuous porosity gradient was prepared via oxidation-gasification reaction between water vapor and W powder particles. The effects were investigated of W powder granularity composition,reaction temperature and time on porosity gradient of the tungsten blank. The microstructure of the sample was observed by metallographic microscope, and the volume fraction of its pores was measured by image analysis software. The results show that porous tungsten blank with continuous porosity gradient can be obtained with oxidation-gasification method, and its porosity decreases gradually from surface to core. Fine tungsten powder is very beneficial to pore construction, and the tungsten blank containing more fine powder has higher porosity and porosity gradient. Higher reaction temperature also results in higher porosity and porosity gradient of the tungsten blank. The longer the reaction time, the higher the porosity and the larger the porosity gradient area of the tungsten blank. Furthermore, surface pores have larger size than core pores of the sample.

Nanocrystalline （Ti,W）（B,C,N） powders were prepared by precursor plus carbothermal reduction with metatitanic acid,ammonium metatungstate,xylose and boracic acid as the materials. Phase composition and microstructure of the products were characterized by SEM and XRD. The effects of synthesis temperature and holding time on reaction products were discussed. The results show that both synthesis temperature and holding time have obvious effects on the synthesis of （Ti,W）（B,C,N） powders. With the increase of synthesis temperature and holding time, synthetic powder grains significantly grow up. Nano- crystalline （Ti,W）（B,C,N） powders with grain size of 21.3 nm are successfully prepared at 1 200 ℃ for 2 h. Compared with the traditional method of ordinary ball milling plus carbothermal reduction, the method of precursor plus carbothermal reduction can significantly reduce synthesis temperature with an advantage of low cost of raw materials.

Al2 O3-doped W powder was prepared by sol-gel, azeotropic distillation and hydrothermal synthesis to produce W-Al2 O3 composite powder by calcination and two-step H2 reduction. Based on XRD analysis and SEM observation, stable monoclinic WOa and metastable hexagonal WO3 were obtained by calcination of Al2 O3-doped W powder prepared with the above-mentioned three methods. The morphology of the powder prepared by hydrothermal synthesis is regular, uniform and spherical. WO3 is reduced to low-valence WO2 and unsaturated-valence WO3-x by the primary H2 reduction,and fine W-Al2 O3 composite powder is obtained by the secondary H2 reduction. Compared with the other two methods, sol-gel method has more obvious refinement effect and it can prepare W-Al2O3 composite powder with nanoscale particle size, since Al2 O3 coated on the surfaces of W particles inhibits the deposition of tungsten atom during subsequent reduction.

Phase stability and electronic properties of pure Cr2 N and Cr2 N doped with transition metals （W, Mo, Nb, Fe, Ni） were investigated by the first-principles calculation based on the density functional theory. Stable Cr23MN12 （M= W, Mo, Nb, Fe, Ni） composite nitride can be formed by replacing Cr with W, Mo, Nb, Fe and Ni in Cr2 N supercells, based on the formation enthalpy and cohesive energy. Among the doping elements,Nb is most easily doped in Cr2 N to form Cr23 NbN12 composite nitride. Cr23 WN12 and Cr23 MoN12 are more stable than pure Cr24N12, due to orbit hybridization of W-5d, Mo-4d and N-2p. Compared with pure Cr2 N, Cr23 FEN12 and Cr23 NiNe2 have reduced stability and enhanced electrochemical activity, owing to the charge transfer from N to Fe and Ni.

In order to ensure the corrosion resistance of the hard seal surface of titanium alloy earth-penetration valve, and improve the hardness, wear resistance and compressive fatigue properties of the valve, laser cladding of pure tantalum was carried out on the surface of TA2 titanium alloy by YAG laser. The metallurgical binding degree, microstructure, component and hardness distribution of layer-cladding Ta coat were analyzed by OM, SEM, EDS and microhardness tester. The results indicate that direct laser cladding of pure Ta powder on TA2 titanium alloy surface is feasible, and there is well metallurgical binding between Ti-Ta alloy coat and the substrate. The dilution of Ti element in laser cladding layer is large,and the dilution decreases with increased distance away from the binding surface. The binding region of laser cladding layer and the substrate is composed mainly of dendrites, and the middle region in the cladding layer is composed of dendrites and partial massive microstructure. The microhardness HV0.2 of the cladding layer is 190- 200, more than 40 higher than that of Ti substrate. The microhardness HV0.2 of the binding region is 200- 220 ,and therefore the hardness gradient is relatively obvious.

The microstructure and mechanical properties of Ti600 high temperature titanium alloy for engine were researched by optical microscope,X-ray diffractometer and mechanical property test. The results show that Ti600 plate is mainly composed of equiaxed primary a grains and a small amount of lamellar α＋β eutectic tissue. Ti600 alloy has small grains and uniform microstructure,and its average gain size is about 2- 4 μm. Ti600 alloy plate has high strength and plasticity at room temperature. With the increase of temperature,tensile strength and yield strength show a weak increasing trend, while elongation rate significantly increases. Ti600 titanium alloy plate is characterized by ductile fracture,with a dimple fracture.

The effect of rare earth Ce on microstructure and mechanical properties of A356 alloy was studied by using OM, SEM, EDS, XRD and universal electronic tensile testing machine. The results indicate that rare earth Ce is an excellent modifier for A356 alloy. Ce is helpful not only for refining the grains of primary α-Al phase,but also for forming small,round and uniform eutectic Si. Rare earth Ce in A356 alloy exists mainly in the form of rare earth intermetallic compound Al11Ce3. When 0.04% Ce is added into A356 alloy,its tensile strength,yield strength and elongation respectively reach 307.5 MPa,239 MPa and 7.72%, increased by 7.89% ,24.48% and 108.09% compared with the alloy without Ce.