YB2powders were prepared by vacuum solid state reaction of YB4 and Y mixed compacts.Process conditions of solid state reaction were studied.The results show that high-purity YB2 powders can be obtained by vacuum solid state reaction at 1 800 ℃for 10 h.

W-Cu composite powders were prepared by hydrothermal synthesis with sodium tungstate and cupric nitrate as the raw materials.The recovery rate was calculated of W-Cu composite powders prepared at different pH.Preparation process of the precursor of W-Cu composite powders was analyzed based on thermodynamics.Phase composition,morphology and microstructure of the prepared W-Cu composite powders were characterized by XRD,SEM,EDS and TEM.The results show that the recovery rates of W and Cu ions are different at different solution concentration and pH value.When sodium tungstate concentration is 0.6mol/L,cupric nitrate concentration is 0.578 6 mol/L and the pH value is 5.5,W and Cu ions precipitate in the form of CuWO4·2H2O,and their recovery rates are more than 99%.The product of hydrothermal synthesis has good dispersivity and uniform particle size of 15~20nm.After calcined at 500℃and reduced with hydrogen at 800℃for 60 min,W-Cu composite powders are obtained with well-distributed W and Cu elements,subglobose microstructure of W-covered Cu and particle size of 100~200nm.

WC reinforced Fe-based composite was prepared by hot pressing sintering with two kinds of Febased pre-alloyed powders of EXD602 and EXDNi105and WC powder as the raw materials.The effects were investigated of different WC content and alloy matrix on microstructure and properties of the composite.The results show that the hardness,density and wear resistance of WC-EXD602 composite are much higher than those of WC-EXDNi105.With the increase of WC content,both hardness and density of WCEXD602 and WC-EXDNi105 composites increase firstly and then decrease,while wear loss decreases firstly and then increases.When the content of WC is 30%,peak hardnesses of WC-EXD602 and WC-EXDNi105 are HRA64.8and HRA48.6,respectively,and the porosity is the lowest.When the content of WC is 45%,wear loss of the two composites is the lowest.WC and alloy matrix alternately frictionize throughout wear process,and the main wear mechanism is abrasive wear.There is no obvious passivation phenomenon in the corrosion polarization curves of WC-EXD602 and WC-EXDNi105 samples.The descending order of the above composites according to their corrosion resistance is as follows:15WC-EXD602>15WC-EXDNi105>75WC-EXDNi105>75WC-EXD602.With WC content increasing,the corrosion resistance of the composites decreases in 3.5% NaCl solution.

WO3and TiO2 thin films were prepared on ITO coated glass substrate by DC magnetron sputtering with sputtering pressure as the variable.And then Li+polymer electrolyte was coated between the two films to assemble solid state electrochromic devices.Phase composition and surface morphology of WO3 thin film were characterized by XRD and AFM.Electrochromic performance of the devices was investigated with DC regulated power supply,and their colored/bleached state transmittance of visible light was determined by spectrophotometer.The results indicate that WO3 film deposited at 1.5Pa contains W metal.Amorphous state WO3 film is achieved at the sputtering pressure of 2.0~3.0Pa.WO3 film deposited at 2.0Pa has long and narrow particle clusters distributed on the surface and relatively large surface area benefiting injection/ejection of Li+and electron during coloration/bleaching,and thus its packaged device achieves the largest modulation amplitude and the fastest response.As sputtering pressure increasing,WO3 films have more surface defects resulting in the electrochromic performance of the devices worsened.

Molten salt electrolysis was done on V-Ti-Fe alloy prepared by metallothermic reduction,and deoxidation process of the alloy was studied.The influence of electrolysis time on deoxidation degree was investigated.The results show that most of oxygen in V-Ti-Fe alloy can be removed by molten salt electrolysis.With the increase of electrolysis time,oxygen content in the alloy gradually decreases to about 0.2%after 240 min electrolysis.Hydrogen absorption and desorption performances of V-Ti-Fe alloy are improved by electro-deoxidation in molten salt.With the increase of electrolysis time,both the maximum hydrogen absorption capacity and the effective hydrogen desorption capacity increase as high as 2.65% and 1.01%,respectively.

The development of several types of hydrogen storage alloys is reviewed,including AB5-type rare earth series hydrogen storage alloy,AB3-type hydrogen storage alloy,AB2-type Laves phase alloy,AB-type Ti series hydrogen storage alloy,Mg-based hydrogen storage alloy,V-based solid solution type hydrogen storage alloy and so on.The development orientation of hydrogen storage alloy is also forecasted.

AlxCoCrFeNi2Tiy(x=0,0.2;y=0,0.5,1)high entropy alloys with multiple principal elements were prepared by non-consumable vacuum arc melting,and the influences were studied of different amounts of Al and Ti elements on alloy oxidation behavior in air at 800℃and 900℃.The results show that all the alloys have a good high-temperature oxidation resistance,and their oxidation kinetic curves follow the parabolic law.Their high-temperature oxidation resistance is enhanced with the increase of Al contents.When there is Al in the alloys,their high-temperature oxidation resistance decreases with the increase of Ti content.However,the oxidation resistance of Al-free alloys increases at first and then decreases with the increase of Ti content.Al0.2CoCrFeNi2 alloy exhibits the optimal high-temperature oxidation resistance,followed by Al0.2CoCrFeNi2Ti0.5.

The influences were investigated of different amounts of Ni element on the microstructure and electrochemical corrosion property of AlFeCoCrCuNix(x=0,0.25,0.5,1)high-entropy alloys by XRD,SEM,EDS and electrochemical polarization curves.The results show that all the alloys exhibit dendritic microstructure with composition segregation,and Cu element is enriched in interdendritic boundaries.Adding a small amount of Ni element results in the formation of granular Al-Ni new phase.With the increase of Ni content,the granular Al-Ni new phase develops into a massive phase distributed between Curich boundary and dendrite.Furthermore,the addition of Ni element improves the corrosion resistance of AlFeCoCrCuNix(x=0,0.25,0.5,1)alloy in 3.5% NaCl solution.And AlFeCoCrCuNi0.5alloy exhibits the optimal corrosion resistance.

AgSnO2electrical contact wire material was prepared by adopting a new integrated process of chemical coating-cold isostatic pressing-hot extrusion and doping trace CuO to improve its machining deformation performance and arc erosion resistance.The room-temperature deformation behavior and arc erosion characteristics of AgSnO2 material were investigated by electronic testing machine,contact material testing system and scanning electron microscope.The results indicate that doping trace CuO improves the wettability of Ag matrix to SnO2 particles and increases the tensile strength and the fracture elongation of AgSnO2 wire.Under the condition of 25V/10 A DC resistance load,AgSnO2(CuO)contact has lower arc energy,arc duration and puddle welding force than AgSnO2 contact,its arc erosion spots have smoother surface,but its contact resistance slightly increases.

SiCP/Al composites were prepared by high pressure torsion(HPT).Changes were analyzed of microstructure,hardness,relative density and SiC particle distribution of the composites with different SiC volume fraction.Densification mechanism was discussed of the composites during high pressure torsion formation.The results show that with the increasing SiC volume fraction,relative density of the composite continually decreases,while both hardness and uniformity of SiC distribution increase firstly and then decrease.And its hardness progressively increases along the radial direction of the sample.With SiC volume fraction increasing,the phenomenon of SiC particle breakage and reunification is more serious.