Practice of Integrating Specialized Courses into Ideological/Political Education——Taking “Solid Luminescent Materials” as an Example

At present,the education of specialized courses in science and engineering still focuses on imparting specialized knowledge,which seriously lacks the embodiment of educating students.Taking the specialized course“Solid Luminescent Materials”as an example,the new mode of ideological/political teaching is integrated into the specialized course,giving full play to the role of the main position of the specialized class,so as to realize the aim of teaching specialized knowledge in cooperation with educating students and imperceptibly influencing the ideological/political teaching.In this paper,the design of ideological/political knowledge points and the integration of ideological/political cases are carried out from the aspects of teaching concepts,teaching contents and teaching cases.By adhering to the cooperation between moral and financial classroom and specialized education,the educational function of university specialized courses can be effectively brought into play,which is expected to guide students to enhance their awareness of energy conservation,environmental protection,innovation and patriotism.

A comprehensive analysis on microstructure evolution of Mg-5.65Zn-0.66Zr alloy during hot deformation

The microstructure evolution of Mg-5.65 Zn-0.66 Zr(wt.%)alloy was studied based on the hot compression tests.The results indicated that the flow stress increased rapidly to a peak point at the initial stage,and then it gradually decreased.Moreover,high temperature and low strain rate resulted in the decreasing of flow stress.All samples exhibited a necklace grain structure because of the occurrence of partial dynamic recrystallization(DRX).High temperature increased both the size and fraction of DRXed grains,while high strain rate showed an opposite tendency.At the conditions of 350°C/0.001 s^(-1)and 350°C/0.1 s^(-1),the twins were not exhibited and DRX played a dominant role.Importantly,the obvious split of basal texture was observed.The pyramidal<c+a>slip with high value of Schmid factor was active in large deformed grains,which corresponded to the peak split point in(0001)pole figure.A mechanism about the grain rotation was proposed to explain the relationship between the pyramidal slip and the split of basal texture.Finally,it was found that large number of{10–12}extension twins were formed during the initial stage at condition of 300°C/1 s^(-1),and the number of twins decreased with the increase of strain.The twins greatly contributed to the fast formation of basal texture and grain rotation.Moreover,the non-basal slips were active in twining region,which could facilitate the nucleation of DRX.

Dealloying induced nanoporosity evolution of less noble metals in Mg ion batteries

Rechargeable Mg ion batteries(MIBs)have aroused great interests,and using alloy-type anodes and conventional electrolytes offers an effective way to develop high energy density Mg battery systems.However,the dealloying-induced nanoporosity evolution of alloy-type anodes during the charging process has received less attention.Herein,using a magnetron-sputtered Mg;Bi;film as an example,we investigate its electrochemical dealloying and associated structural evolution in an all-phenyl-complex electrolyte by in-situ and ex-situ characterizations.The microstructures and length scales of nanoporous Bi can be facilely regulated by changing electrochemical parameters,and there exists a good linear correlation between the surface diffusivity of Bi and the applied current density/potential scan rate on a logarithm scale.More importantly,the self-supporting nanoporous Bi electrodes deliver satisfactory Mg storage performance and alloy-type anodes show good compatibility with conventional electrolytes.Furthermore,the charging-induced dealloying in MIBs is a general strategy to fabricate nanoporous less noble metals like Sn,Pb,In,Cu,Zn and Al,which shows advantages over chemical dealloying in aqueous solutions.Our findings highlight the significance of nanoporosity evolution of alloy-type anodes during dealloying,and open opportunities for the fabrication of nanoporous reactive metals.

Experimental study on tensile deformation behaviors under room and elevated temperatures induced by microstructure inhomogeneity of ZK60 Mg with a longitudinal weld

The tensile tests of the extruded ZK60 Mg containing a longitudinal weld seam were carried out at room and elevated temperatures, and the effects of induced microstructure inhomogeneity on tensile deformation behavior was clarified. The results show that the deformation mode, dynamic recrystallization(DRX), texture evolution and mechanical properties are strongly affected by the longitudinal weld seam,temperature, and loading direction. The room temperature(RT) deformation of welding zone is controlled by the dislocation slips with the association of some twins, while twinning plays significant roles in the accommodation of c-axis strain of the coarse grains on matrix zone.The deformation at RT stretched along extrusion direction(ED) and transverse direction(TD) are controlled by basal slip/twinning and basal slip/prismatic slip/twinning, respectively. During high temperature tension, the dislocation cross slip of pyramidal slip is activated, and grain boundary sliding occurred in welding zone, leading to the superplastic behavior. With the increase of tensile temperature, the predominant DRX mode is transformed from continuous DRX to discontinuous DRX. Moreover, the basal poles of the grains spread from TD towards ED with the decrease of maximum pole intensity when stretched along ED, while non-basal textures are transformed to (10-10) fiber texture when stretched along TD. The slip-dominated flow is seen during RT tension along ED, while twinning becomes predominant during RT tension along TD. The fine grain structure causes the superior RT tensile properties along ED of welding zone with ultimate tensile strength of 315 MPa and elongation to failure of 13.8%. With the increase of tensile temperature, the slipping-dominated deformation is transformed into twinning-dominated, causing the decrease of strength and increase of elongation.

Rational design of F,N-rich artificial interphase via chemical prelithiation initiation strategy enabling high coulombic efficiency and stable micro-sized SiO anodes

Silicon monoxide(SiO)is regarded as a potential candidate for anode materials of lithium-ion batteries(LIBs).Unfortunately,the application of SiO is limited by poor initial Coulombic efficiency(ICE)and unsteady solid electrolyte interface(SEI),which induce low energy,short cycling life,and poor rate properties.To address these drawbacks of SiO,we achieve in-situ construction of robust and fast-ion conducting F,N-rich SEI layer on prelithiated micro-sized SiO(P-μSiO)via the simple and continuous treatment ofμSiO in mild lithium 4,4′-dimethylbiphenyl solution and nonflammable hexafluorocyclotriphosphazene solution.Chemical prelithiation eliminates irreversible capacity through pre-forming inactive lithium silicates.Meanwhile,the symbiotic F,N-rich SEI with good mechanical stability and fast Li^(+)permeability is conductive to relieve volume expansion ofμSiO and boost the Li+diffusion kinetics.Consequently,the P-μSiO realizes an impressive electrochemical performance with an elevated ICE of 99.57%and a capacity retention of 90.67%after 350 cycles.Additionally,the full cell with P-μSiO anode and commercial LiFePO_(4) cathode displays an ICE of 92.03%and a high reversible capacity of 144.97 mA h g^(-1).This work offers a general construction strategy of robust and ionically conductive SEI for advanced LIBs.

High strength mullite-bond SiC porous ceramics fabricated by digital light processing

Fabricating SiC ceramics via the digital light processing(DLP)technology is of great challenge due to strong light absorption and high refractive index of deep-colored SiC powders,which highly differ from those of resin,and thus significantly affect the curing performance of the photosensitive SiC slurry.In this paper,a thin silicon oxide(SiO_(2))layer was in-situ formed on the surface of SiC powders by pre-oxidation treatment.This method was proven to effectively improve the curing ability of SiC slurry.The SiC photosensitive slurry was fabricated with solid content of 55 vol%and viscosity of 7.77 Pa·s(shear rate of 30 s^(−1)).The curing thickness was 50μm with exposure time of only 5 s.Then,a well-designed sintering additive was added to completely convert low-strength SiO_(2) into mullite reinforcement during sintering.Complexshaped mullite-bond SiC ceramics were successfully fabricated.The flexural strength of SiC ceramics sintered at 1550℃in air reached 97.6 MPa with porosity of 39.2 vol%,as high as those prepared by spark plasma sintering(SPS)techniques.

Microstructure and properties of low-temperature aged Dy-doped Nd-Fe-B magnet

In this work, a low temperature ageing process for the high coercivity Dy-doped Nd-Fe-B magnets was developed by the optimizing ageing process. The experimental results show that there is no difference in microstructures, crystal orientation, magnetic and mechanical properties between the low-temperature aged and the two-stage aged sintered Dy-doped Nd-Fe-B magnets. Because of the uneven stress distribution in the sintered Dy-doped Nd-Fe-B magnet and the high activation of Dy element, Dy atoms could diffuse into the main crystal phase and the grain boundary phases of the magnets during low-temperature ageing process, which results in the reasonable distribution of Dy element and formation of the thin and uniform grain boundary phases, which are the main reasons to improve intrinsic coercivity of the Dy-doped Nd-Fe-B magnets by the low-temperature ageing.

Rationally designed hollow carbon nanospheres decorated with S,P co-doped NiSe_(2) nanoparticles for high-performance potassium-ion and lithium-ion batteries

Hollow nanostructures with external shells and inner voids have been proved to greatly shorten the transport distance of ions/electrons and buffer volume change,especially for the large-sized potassium-ions in secondary batteries.In this work,hollow carbon(HC) nanospheres embedded with S,P co-doped NiSe_(2)nanoparticles are fabricated by "drop and dry" and "dissolving and precipitation" processes to form Ni(OH)2nanocrystals followed by annealing with S and P dopants to form nanoparticles.The resultant S,P-NiSe_(2)/HC composite exhibits excellent cyclic performance with 131.6 mA h g^(-1)at1000 mA g^(-1)after 3000 cycles for K^(+)storage and a capacity of 417.1 mA h g^(-1)at 1000 mA g^(-1)after1000 cycles for Li^(+)storage.K-ion full cells are assembled and deliver superior cycling stability with a ca pacity of 72.5 mA h g^(-1)at 200 mA g^(-1)after 500 cycles.The hollow carbon shell with excellent electrical conductivity effectively promotes the transporta tion and tolerates large volume variation for both K^(+)and Li^(+).Density functional theory calculations confirm that the S and P co-doping NiSe_(2) enables stronger adsorption of K^(+)ions and higher electrical conductivity that contributes to the improved electrochemical performance.

Self-Supporting Nanoporous Copper Film with High Porosity and Broadband Light Absorption for Efficient Solar Steam Generation

Solar steam generation(SSG)is a potential technology for freshwater production,which is expected to address the global water shortage problem.Some noble metals with good photothermal conversion performance have received wide concerns in SSG,while high cost limits their practical applications for water purification.Herein,a self-supporting nanoporous copper(NP-Cu)film was fabricated by one-step dealloying of a specially designed Al_(98)Cu_(2)precursor with a dilute solid solution structure.In-situ and ex-situ characterizations were performed to reveal the phase and microstructure evolutions during dealloying.The NP-Cu film shows a unique three-dimensional bicontinuous ligament-channel structure with high porosity(94.8%),multi scale-channels and nanoscale ligaments(24.2±4.4nm),leading to its strong broadband absorption over the 200–2500 nm wavelength More importantly,the NP-Cu film exhibits excellent SSG performance with high evaporation rate,superior efficiency and good stability.The strong desalination ability of NP-Cu also manifests its potential applications in seawater desalination.The related mechanism has been rationalized based upon the nanoporous network,localized surface plasmon resonance effect and hydrophilicity.

Microstructure evolution of spray deposited and as-cast 2195 Al-Li alloys during homogenization

In this paper,a comparative study on the spray deposited and as-cast 2195 alloy was carried out to reveal their microstructure evolutions and differences during the homogenization process.The dissolution of the secondary particles and the diffusion of solute were studied based on microstructure characterization and kinetics analysis.The precipitation behavior of Al3Zr dispersoids and its influence on recrystallization were investigated by using TEM and EBSD characterization.It was found that the large-size particles at triangular grain boundaries dissolve slower than the intragranular phases and other grain boundary phases.The required homogenization time depends on the dissolution processes of the large-size phases at grain boundaries.The size of grain boundary phases in the spray deposited alloy is much smaller than that in the as-cast alloy,so the homogenization time required for the spray deposited alloy is significantly shorter.Two-stage and ramp heating homogenization processes can promote the precipitation of Al3Zr dispersoids in the two alloys.In the spray deposited alloy,the dispersoids tend to precipitate at the positions of the T1 plates dissolved,which causes a non-uniform distribution and decreases the recrystallization resistance of the alloy.However,the distribution of the dispersoids in the as-cast alloy is more uniform after the homogenization,which brings a stronger inhibition on the recrystallization.According to the microstructural characterization and kinetics analysis results,it can be concluded that the homogenization with a slow ramp heating is suitable for the two 2195 alloys,and a shorter holding time can be used for spray deposited alloy,e.g.12 h at 500℃,while the holding time for the as-cast alloy is no less than 35 h at 500℃.

Self-supporting nanoporous gold-palladium overlayer bifunctional catalysts toward oxygen reduction and evolution reactions

The oxygen reduction reaction （ORR） and oxygen evolution reaction （OER） are crucial processes for energy conversion/storage systems, such as fuel cells, metal-air batteries, and water splitting. However, both reactions are severely restricted by their sluggish kinetics, thus requiring highly active, cost-effective, and durable electrocatalysts. Herein, we develop novel bifunctional nanocatalysts through surface nanoengineering of dealloying-driven nanoporous gold （NPG）. Pd overlayers were precisely deposited onto the NPG ligament surface by epitaxial layer-by-layer growth. More importantly, the obtained NPG-Pd overlayer nanocatalysts exhibit remarkably enhanced electrocatalytic activities toward both the ORR and OER in alkaline media, benchmarked against a state- of-the-art Pt/C catalyst. The improved electrocatalytic performance is rationalized by the unique three-dimensional nanoarchitecture of NPG, enhanced Pd utilization efficiency from precise control of the Pd overlayers, and change in electronic structure, as revealed by density functional theory calculations.

Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures

Te mechanism of negative permittivity/permeability is still unclear in the random metamaterials,where the precise control of microstructure and electromagnetic properties is also a challenge due to its random characteristic.Here silver was introduced into porous SiO_(2) microsphere matrix by a self-assemble and template method to construct the random metamaterials.Te distribution of silver was restricted among the interstices of SiO_(2) microspheres,which lead to the precise regulation of electrical percolation(from hoping to Drude-type conductivity)with increasing silver content.Negative permittivity came from the plasma-like behavior of silver network,and its value and frequency dispersion were further adjusted by Lorentz-type dielectric response.During this process,the frequency of epsilon-near-zero(ENZ)could be adjusted accordingly.Negative permeability was well explained by the magnetic response of eddy current in silver micronetwork.Te calculation results indicated that negative permeability has a linear relation with ω^(0.5),showing a relaxation-type spectrum,diferent from the“magnetic plasma”of periodic metamaterials.Electromagnetic simulations demonstrated that negative permittivity materials and ENZ materials,with the advantage of enhanced absorption(40dB)and intelligent frequency selection even in a thin thickness(0.1 mm),could have potentials for electromagnetic attenuation and shielding.Tis work provides a clear physical image for the theoretical explanation of negative permittivity and negative permeability in random metamaterials,as well as a novel strategy to precisely control the microstructure of random metamaterials.

Tuning Surface Spin Polarization of CoFeB by Boron Diffusion Detected by Spin Resolved Photoemission

Research of spin polarization of magnetic CoFeB thin films is of practical importance in spintronic applications.Here,using a direct characterization technique of spin-resolved photoemission spectroscopy,we obtain the surface spin polarization of amorphous Co_(40)Fe_(40)B_(20)thin films with different annealing temperatures from 100℃to 500℃prepared by magnetron sputtering.After high annealing temperature,a quasi-semiconductor state is gradually formed at the CoFeB surface due to the boron diffusion.While the global magnetization remains almost constant,the secondary electrons’spin polarization,average valence band spin polarization and the spin polarization at Fermi level from spin-resolved photoemission spectroscopy show a general trend of decreasing with the increasing annealing temperature above 100℃.These distinct surface properties are attributed to the enhanced Fe-B bonding due to the boron segregation upon surface after annealing as confirmed by x-ray photoelectron spectroscopy and scanning transmission electron microscopy with energy dispersive spectroscopy.Our findings provide insight into the surface spin-resolved electronic structure of the CoFeB thin films,which should be important for development of high-performance magnetic random-access memories.

超声振动对AZ31镁合金拉伸变形过程中材料性能及微观组织影响的研究（英文）

超声振动塑性成形技术能显著降低设备成形力,减少模具与工件间的摩擦,可有效提高制品的表面质量和尺寸精度。通过进行AZ31镁合金退火态棒材常规拉伸和不同激振方式条件下的振动拉伸实验,对比不同实验条件下的变形载荷曲线,拉伸试样断裂方式,显微硬度值,晶粒形状、尺寸的变化,研究超声振动在AZ31镁合金拉伸变形中的作用。结果表明,施加超声振动条件不同,真实应力下降幅度不同,最大降幅为4.76%。沿着试样拉伸方向所取3个点的最大硬度差为HV 10.9。AZ31镁合金的断裂方式、塑性和显微组织也受超声振动幅值和作用时间的影响。超声振动作用下,软化效应和硬化效应同时发生。当振幅为4.6μm,且作用时间较短时,塑性变形以孪晶为主,软化效应占主导地位。当超声能量较高时,孪生被抑制,硬化效应占主导地位。

Ternary mesoporous cobalt-iron-nickel oxide efficiently catalyzing oxygen/hydrogen evolution reactions and overall water splitting

Among various efficient electrocatalysts for water splitting,CoFe and NiFe-based oxides/hydroxides are typically promising candidates thanks to their extraordinary activities towards oxygen evolution reaction (OER).However,the endeavor to advance their performance towards overall water splitting has been largely impeded by the limited activities for hydrogen evolution reaction (HER).Herein,we present a CoFeNi ternary metal-based oxide (CoFeNi-O) with impressive hierarchical bimodal channel nanostructures,which was synthesized via a facile one-step dealloying strategy.The oxide shows superior catalytic activities towards both HER and OER in alkaline solution due to the alloying effect and the intrinsic hierarchical porous structure.CoFeNi-O loaded on glass carbon electrodes only requires the overpotentials as low as 230 and 278 mV to achieve the OER current densities of 10 and 100 mA·cm-2,respectively.In particular,extremely low overpotentials of 200 and 57.9 mV are sufficient enough for Ni foam-supported CoFeNi-O to drive the current density of 10 mA·cm-2 towards OER and HER respectively,which is comparable with or even better than the already-developed state-of-the-art non-noble metal oxide based catalysts.Benefiting from the bifunctionalities of CoFeNi-O,an alkaline electrolyzer constructed by the Ni foam-supported CoFeNi-O electrodes as both the anode and the cathode can deliver a current density of 10 mA·cm-2 at a fairly low cell-voltage of 1.558 V.In view of its electrocatalytic merits together with the facile and cost-effective dealloying route,CoFeNi-O is envisioned as a promising catalyst for future production of sustainable energy resources.

Achieving three-layered Al/Mg/Al sheet via combining porthole die co-extrusion and hot forging

Al/Mg/Al sheet with good bonding quality and mechanical properties was fabricated based on the proposed porthole die co-extrusion and forging(PCE-F)process.There were no voids,cracks or other defects on the Al/Mg interface.A continuous diffusion zone with two-sub-layer structure was formed across the Al/Mg interface,and its width increased with higher temperature or reduction ratio.The sub-layers formed at low and high temperature were identified to be solid solutions and intermetallic compounds(IMCs)including y-MgpAl^and^-Al3Mg.In Al layer,the welding zone mainly consisted of fine equiaxed grains with several coarse elongated grains,while the majority of matrix zone is coarse elongated grains.The rolling textures were dominated in both welding and matrix zones.In Mg layer,the welding zone exhibited complete DRXed grain structure,while several unDRXed coarse grains were observed in the matrix zone.With the increasing temperature,the grain size of Al and Mg layer firstly decreased and then increased.High reduction ratio strongly refined the grain structure of Al layer,while slightly affected the Mg layer.The Al/Mg/AI sheet experienced stress-drops twice during the tensile test.The first stress-drop was determined by the IMCs and microstructure of Mg layer,while the second stress-drop was closely related to the microstructure of Al layer.Al/Mg/Al sheet forged at the lowest temperature without the formation IMCs exhibited the highest stress for the first stress-drop,and that forged under the highest reduction ratio with the smallest grain size in Al layer had the highest stress for the second stress-drop.

Formation mechanism and evolution of surface coarse grains on a ZK60 Mg profile extruded by a porthole die

Porthole die extrusion of Mg alloys was studied by means of experimental and numerical studies. Results indicated that an inhomogeneous microstructure formed on the cross-section of the extruded profile. On the profile surface, abnormal coarse grains with an orientation of <11-20> in parallel to ED(extrusion direction) appeared. In the profile center, the welding zone was composed of fine grains with an average size of 4.19 um and an orientation of <10-10> in parallel to ED, while the matrix zone exhibited a bimodal grain structure. Disk-like, near-spherical and rod-like precipitates were observed, and the number density of those features was lower on the profile surface than that in the profile center. Then, the formation and evolution of coarse grains on the profile surface were investigated, which were found to depend on the competition between static recrystallization and grain growth. The stored deformation energy was the factor dominating the surface structure through effective regulation over nucleation of the precipitates and recrystallization. A profile with a low stored deformation energy suppressed formation of precipitates and consequently facilitated grain growth rather than recrystallization, resulting in the formation of abnormal coarse grains. Finally, the surface coarse grains contributed detrimentally to hardness, tensile properties, and wear performance of the bulk structure.

Hot deformation behavior and constitutive relationship of Q420qE steel

Isothermal compression tests at temperatures from 1 273 to 1 423 K and strain rates from 0.1 to 10 s-1 were carried out to investigate the flow behaviors of Q420qE steel.Stress-strain data collected from the tests were employed to establish the constitutive equation,in which the influence of strain was incorporated by considering the effect of strain on material constants Q,n,α,and ln A.The results show that the flow stress curves are dependent on the strain,strain rate and deformation temperature.They display typical dynamic recrystallization behavior and consist of three stages,i.e.,hardening stage,softening stage and steady stage.The flow stress decreases with increasing the deformation temperature and decreasing the strain rate.In addition,the flow stress data predicted by the proposed constitutive model agree well with the corresponding experimental results,and the correlation coefficient and the average absolute relative error between them are 0.990 3 and 3.686%,respectively.

Operando X-ray diffraction analysis of the degradation mechanisms of a spinel LiMn2O4 cathode in different voltage windows

The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries.The LiMn2O4 cathode has a voltage plateau around 2.8 V(vs.Li^+/Li),which can provide an additional capacity for Li storage,but it suffers from a severe capacity degradation.In this study,operando X-ray diffraction is carried out to investigate the structural evolutions and degradation mechanisms of LiMn2O4 in different voltage ranges.In the range of 3.0-4.3 V(vs.Li^+/Li),the LiMn2O4 cathode exhibits a low capacity but good cycling stability with cycles up to 100 cycles and the charge/discharge processes are associated with the reversible extraction/insertion of Li^+from/into LixMn2O4(0≤x≤1).In the range of 1.4-4.4 V(vs.Li^+/Li),a capacity higher than 200 mAh/g is achieved,but it rapidly decays during the cycling.The voltage plateau around 2.8 V(vs.Li^+/Li)is related to the transformation of the cubic LiMn2O4 phase to the tetragonal Li2Mn2O4 phase,which leads to the formation of cracks as well as the performance degradation.

Detection of Ordered Molecules Adsorbed on Graphene： a Theoretical Study

Graphene 被表明了能检测单个煤气的分子[Schedin 等。Nat。母亲。6 (2007 ) 652 ] ，它吸引了很多传感器研究活动。这里，我们第一次报导 graphene 能够检测吸收的水分子的订的度。做的效率从分子的订的度变化。模仿的结果证明高度订的水分子贡献更多到做的效果，它减少 water/graphene 系统的传导力。