Copper alloys are extensively utilized in electronics,aerospace,and mechanical manufacturing sectors owing to their superior electrical conductivity,thermal conductivity,and mechanical properties.With the progression of high-end equipment towards enhanced performance,traditional single-phase dispersion-strengthened copper alloys struggle to meet the increasingly rigorous service requirements.Consequently,there is a pressing need for the development of high-performance dual-phase dispersion-strengthened co-pper alloys.This study employed microwave sintering to prepare Cu-3%WC-xY composites and investiga-ted the effects of different microwave sintering processes,Y addition amount,and annealing processes on their microstructure and comprehensive properties.The results reveal that as the microwave sintering tem-perature increases,the surface porosity of Cu-3%WC-0.15%Y composites decreases significantly,while their relative density,hardness,electrical conductivity,flexural strength,and yield strength increase gradu-ally.Prolonging the sintering time results in a gradual increase in the grain size of Cu-3%WC-0.15%Y composites,accompanied by rising electrical conductivity and relative density,while the hardness,flexural strength,and yield strength first increase and then decrease.With increasing Y addition amount,the rela-tive density and hardness of Cu-3%WC-xY composites first increase and then decrease,while the electrical conductivity exhibits an overall downward trend.Moreover,Y in the composites is mainly segregated around WC particles,which improves interfacial bonding and strengthens the material.Under the optimized conditions of a microwave sintering temperature of 1050℃,a sintering time of 90 min,and a Y addition amount of 0.15%,the Cu-3%WC-xY composite demonstrates relatively favorable comprehensive proper-ties:Its relative density,electrical conductivity,hardness,flexural strength,and yield strength are 86.4%,66.1%IACS,54.8 HV,270.73 MPa,and 28.96 MPa,respectively.Elevating the annealing temperature or extending the annealing time leads to grain coarsening in Cu-3%WC-0.15%Y composites and a notable en-hancement in electrical conductivity.When annealed at 800℃for 2 h,the composite exhibits an electrical conductivity of 77.1%IACS,an increase of 16.64%compared with the unannealed sample.

FeCoCrNiMo_0.75 high-entropy alloys prepared by vacuum arc melting were subjected to laser sur-face remelting modification treatment.The effects of different laser powers(300~1500 W)on the remel-ted microstructure,hardness,and friction and wear properties of FeCoCrNiMo_0.75 alloy were investigated using XRD,SEM-EDS,a microhardness tester,and a reciprocating friction and wear tester.The results show that the thickness of the remelted layer increases with increasing laser power.The microstructure of the alloy without remelting treatment is mainly composed of FCC,σphase andμphase.After remelting at low power(300~600 W),the phase composition does not change significantly.When the laser power is in-creased to 900~1500 W,theμphase in the remelted microstructure disappears.Laser remelting can signi-ficantly refine the eutectic microstructure of the alloy and improve its surface hardness and friction and wear properties.Among them,FeCoCrNiMo_0.75 high-entropy alloy remelted at 600 W laser power has the optimal comprehensive performance,with the highest average hardness of the remelted layer(573 HV_0.2).In addition,its friction coefficient,surface roughness,and volumetric wear rate are all the lowest,and the volumetric wear rate is reduced by 85.5%compared with the alloy without remelting.In terms of wear mechanisms,the room-temperature wear mechanism of the alloy without remelting is mainly abrasive wear and fatigue wear.However,after the alloy is subjected to laser surface remelting treatment,its wear mecha-nism is mainly abrasive wear.

To realize the resource utilization of rare earth tailings and develop high-efficiency NH₃-SCR de-nitration catalysts,Bayan Obo rare earth tailings were used as raw material to prepare catalysts in this study.By combining orthogonal experiments and multi-objective decision-making,the regulation laws of synergistic activation process parameters of high-energy ball milling and microwave roasting on the deni-tration performance and microstructure of the prepared catalysts were systematically investigated.The op-timal parameter combinations and the sensitivity of each parameter under different weight objectives of de-nitration efficiency and N2 selectivity were determined.The results show that the synergistic activation process of high-energy ball milling and microwave roasting can effectively activate the active components in rare earth tailings and significantly improve their catalytic performance.Under appropriate process condi-tions,the rare earth tailings catalyst exhibits a greatly enhanced denitration efficiency within the tempera-ture window of 200~400℃,together with excellent N2 selectivity.As determined by comprehensive per-formance index optimization,the optimal combination of process parameters is identical under different weight ratios of denitration efficiency and N2 selectivity:ball milling time 2 h,ball milling speed 300 r/min,ball-to-powder mass ratio 1∶1,diameter ratio of large,medium and small grinding balls 1∶1∶1,micro-wave roasting temperature 350℃,microwave roasting time 20 min,and microwave power 1100 W.The ball-to-powder mass ratio is the most sensitive factor among all the investigated schemes,and the sensitivi-ty of high-energy ball milling parameters is generally significantly higher than that of microwave roasting parameters,confirming that high-energy ball milling plays a dominant role in promoting mineral dissocia-tion and exposing active sites.Therefore,high-energy ball milling parameters,especially the ball-to-powder mass ratio,should be preferentially regulated in practical process optimization.This study provides syste-matic process guidance and theoretical support for the low-cost preparation of catalysts based on rare earth tailings and the regulation of their denitration performance.

The rare earth concentrate was treated by ball milling and sulfuric acid leaching,and then Cu and Fe were loaded on the mineral surface by hydrothermal method to prepare modified rare earth concentrate catalysts.The effects of Cu and Fe mass ratio,roasting temperature and other factors on the performance of the catalyst were studied.By XRD,SEM,EDS,BET,H2-TPR and XPS,the surface morphology,micro-structure,redox ability and element valence distribution of the catalyst were analyzed,and the mechanism of denitration performance improvement was clarified.The results show that the loading of Cu and Fe on the rare earth concentrate catalyst treated by ball milling and acidification modification can effectively im-prove the denitration performance of the catalyst.When the mass ratio of Cu to Fe is 0.75∶1,the NO_x conversion rate of the catalyst is the highest,reaching 96%at the flue gas temperature of 350°C,which is 77 percentage points higher than that of the raw ore.The introduction of Cu species helps to improve the denitration activity of the catalyst in the low temperature stage.After loading Cu and Fe,the relative con-tent of Fe³⁺ on the surface of the catalyst increases,and Fe₂O₃ can act as active sites to improve the deni-tration performance of the catalyst.The relative content of lattice oxygen increases,and the valence change of Ce on the mineral surface is not inhibited,ensuring the conversion of oxygen species.

To address the issues of coarse microstructure and low efficiency of conventional solution treat-ment in ZL114A aluminum alloy,modification treatment of the alloy was carried out by adding 0.25%(mass fraction)La-Ce mixed rare earth.Plused magnetic field solution treatment was performed at 530℃for 6 h,8 h,and 10 h using a self-developed pulsed magnetic field heat treatment apparatus,with the 10 h conventional solution treatment as a control group.The effects of pulsed magnetic field solution treatment on the microstructure and properties of the alloy were systematically investigated.The results show that the microstructure and hardness of La-Ce modified ZL114A aluminum alloy after pulsed magnetic field so-lution treatment are superior to those of conventional solution treatment for 10 h.Among them,the 8 h pulsed magnetic field solution treatment exhibits the optimal effect.Compared with the 10 h conventional solution treatment,it reduces the aspect ratio of eutectic silicon by 24.3%,decreases the average size by 32.7%,increases the hardness by 17%,and results in a more homogeneous distribution of rare earth ele-ments.Mechanism analysis shows that the pulsed magnetic field provides an extra diffusion driving force for solute atoms via the current path distortion effect,effectively reducing the diffusion activation energy,thereby accelerating the cracking and spheroidization of eutectic silicon and promoting the dispersed distri-bution of rare earth elements.The pulse magnetic field solution treatment process can shorten the conven-tional solution treatment time by at least 2 h while ensuring or even improving solution quality,thereby significantly enhancing production efficiency.This study provides theoretical and technological references for the efficient production and quality improvement of rare earth-modified ZL114A aluminum alloy.

In order to achieve efficient and balanced utilization of rare earth resources,this study used mis-chmetal(MM)rich in La and Ce as the main raw material.Nd/MM-Fe-B composite hot-pressed and hot-deformed magnets were fabricated by the dual main-phase process combined with spark plasma sintering(SPS)technology.The evolution of magnetic properties,microstructure and coercivity mechanism of mag-nets with different mischmetal contents was systematically investigated.The results show that when the ratio of mischmetal to total rare earth increases from 0 to 30.61%,the remanence of the magnet decreases from 13.38 kGs to 11.96 kGs,while the coercivity decreases from 12.79 kOe to 11.01 kOe.With increa-sing mischmetal content,the rare-earth-rich phase is squeezed out of grain boundaries at high temperature and high pressure,leading to an increased proportion of equiaxed coarse-grained regions and ultimately reducing the remanence and coercivity of the hot-pressed and hot-deformed magnets.The intergranular ex-change coupling of the magnets gradually weakens,the long-range magnetostatic interaction strengthens,the irreversible susceptibility decreases,the consistency of magnetization reversal deteriorates,the pinning effect weakens,and thus the coercivity degrades.

The effects of annealing process parameters(temperature and holding time)on the microstruc-ture and mechanical properties of cold-rolled Ti-2Al-2.5Zr titanium alloy tubes were systematically investi-gated using XRD,OM,SEM,EBSD,and tensile testing.The strengthening-toughening mechanisms of the annealed tubes were also analyzed.The results indicate that annealing at 700℃for 1.5~2.0 h leads to complete recrystallization of the cold-rolled tubes,resulting in a homogeneous fine-grained microstructure with an average grain size below 25μm.This microstructure exhibits a high yield strength of 436 MPa and a peak elongation of 27.5%.Grain refinement is identified as the dominant strengthening-toughening mechanismof the annealed tubes,leading to a significant enhancement of both strength and plasticity.Du-ring plastic deformation,the annealed tubes deform mainly via prismatic slip,complemented by pyramidal slip to accommodate strain.This study elucidates the microstructure-mechanical property relationship in annealed Ti-2Al-2.5Zr tubes,thereby providing a theoretical basis and process optimization guidelines for their application in nuclear and aerospace industries.

TC4ELI-TC21 gradient titanium alloy material was fabricated via laser deposition manufacturing(LDM).To investigate the feasibility of simultaneously applying micro-casting and forging during the addi-tive manufacturing process of this gradient material,thermal compression tests were conducted at tempera-tures of 850℃,900℃,950℃and 1000℃and strain rates of 0.01 s^-1,0.1 s^-1,1 s^-1 and 10 s^-1.The in-fluence of deformation temperature and strain rate on the peak stress and microstructural evolution beha-vior was analyzed.The results indicate that the TC4ELI-TC21 gradient titanium alloy fabricated by LDM exhibit highly consistent microstructural evolution and integrated mechanical behavior during thermal de-formation.The alloy demonstrates pronounced dynamic softening at elevated temperatures,with peak stress decreasing with increasing temperature and increasing with increasing strain rate.As the deformation temperature increases,the lamellarαphase undergoes dynamic recrystallization,transforming into equiaxedαphase.Furthermore,the volume fraction of equiaxedαphase gradually decreases with increasing strain rate.When the deformation temperature reaches 1000℃,a martensitic transformation occurs within the material,resulting in a microstructure dominated by martensite.Based on the hyperbolic sine-modified Ar-rhenius model,the constitutive equation and thermal processing map were established for the thermal de-formation of LDM-fabricated TC4ELI-TC21 gradient titanium alloy.Based on the instability regions and power dissipation characteristics revealed by the thermal processing map,the optimal thermal deformation process window for this alloy is determined to be a deformation temperature of 900~950℃and a strain rate of 0.01~0.1 s^-1.

Ti(C,N)-based cermets have become ideal substitutes for traditional WC-based cermets owing to their abundant resources,low cost,and excellent physicochemical properties.Nanometer Ti(C,N)-based cermets exhibit significant advantages in cutting processing,advanced ceramics,hard coatings,and other fields due to grain refinement and further improved hardness and toughness.Preparing nano-Ti(C,N)pre-cursor powders with controllable grain size and favorable dispersibility is an effective strategy to enhance the performance of cermets.This paper summarizes the synthesis technologies and recent advances in ultra-fineano Ti(C,N)powders worldwide,and provides an in-depth analysis of the reaction mechanisms,process characteristics,and product properties of each method.Although carbothermal reduction and nitri-dation is the dominant technique for industrial production,it still suffers from drawbacks such as high en-ergy consumption and uneven particle size distribution.Other methods also face challenges including grain agglo-meration and broad particle size distribution.In the future,efforts should focus on developing preparation processes with high efficiency and economic viability,achieving precise control over the grain size of Ti(C,N)solid-solution powders,and effectively alleviating agglomeration,thereby laying a solid foundation for the widespread promotion and in-depth application of Ti(C,N)-based cermets in industrial field.

During high-temperature,high-reduction deformation,beryllium is susceptible to contamination by free impurity elements originating from the A3 and S45 steels used for pack rolling and superimposed rolling.Specifically,Fe and Si primarily reside on the surface layer of the deformed beryllium through ad-sorption,while Mn and C accumulate via diffusion.This study investigated the influence law of free impuri-ty content on the surface strength,hardness,and plasticity of deformed beryllium.Effective control of Fe/Si and Mn/C impurities was achieved through weak acid cleaning and ultrasonic cleaning,respectively.The results indicate that an increase in free impurity content significantly enhances surface strength and hard-ness but reduces elongation after fracture.As point defects,free impurities hinder dislocation movement and promote excessive grain refinement,which strengthens the material while simultaneously impairing its plasticity.Weak acid cleaning effectively reduces Fe and Si impurities,whereas ultrasonic cleaning signifi-cantly decreases Mn and C impurities.This research confirms that rational control of the free impurity con-tent in deformed bery-llium surface can achieve a balance between strength,hardness,and plasticity,provi-ding a theoretical and technical foundation for the preparation of high-performance beryllium materials.