最新刊期
卷 29 ， 期 9 ， 2009
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- 摘要：An apparent viscosity model of the semi-solid AZ91D magnesium alloy was established by fitting the testing data,and filling process of semi-solid AZ91D slurry for the connecting rod was simulated. The simulated result was well in agreement with experimental one,exhibiting the availability of the established model. Processing parameters for die casting semi-solid connecting-rod were optimized by simulation. Appropriate processing parameters are as follows:the forming temperature more than 590℃,filling velocity of the ingate more than 2.7m/s and injecting pressure more than 40MPa.关键词：Semi-solid;AZ91D Magnesium Alloy;Rheo-diecasting;Numerical Simulation
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发布时间：2023-12-18 - 摘要：Thermal expansion,mechanical properties and microstructure of Al-20Si-1Ni-xMg alloys were described. The results reveal that,with 0.4% Mg content,thermal expansion coefficient of the high Si aluminum alloy modified by P and RE reaches 17.4×10-6/℃. The tensile strength of the alloy containing Mg can be greatly improved after T6 heat treatment,where the maximum value can be observed with approximately 0.4% Mg content,which is attributed to the precipitation of Mg2Si phase during heat treatment. Both primary Si phase and eutectic Si phase can be refined with P-RE compound modification,however,the Mg content has not obvious effects on P-modified primary Si phase. The fracture morphology of the high Si aluminum alloy is characterized by mixed rupture modes of ductile rupture of Al matrix and brittle rupture of Si particle.关键词：High Si Aluminum Alloy;Microstructure;Mechanical Properties;Modification;Thermal Expansion
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发布时间：2023-12-18 - 摘要：AZ31B magnesium alloy strip was cast-rolled by experimental vertical twin-roll caster to understand the microstructure of the twin-rolling casting strip. The microstructure of the casting-rolling magnesium alloy strip was observed in condition of varied processing parameters and different cooling rates. The results reveal that fine grain in microstructure of twin-rolled magnesium alloy can be observed in the absence of eutectoid composition. Microstructure of the rolling-casting magnesium alloy strip is closely related to the rolling velocity,where desirable equiaxed crystal can be exhibited in the magnesium alloy strip with rolling at 20 m/min. Surface oxidation on the as-cast strip can be eliminated and the grain growth can be restrained by quenching the strip in oil.关键词：Twin-rolling Casting;Thin Strip;Magnesium Alloy;Microstructure
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发布时间：2023-12-18 - 摘要：Modification surface treatment of ZM5 Mg alloy by high-energy micro-arc spark alloying S331 was conducted to improve the corrosion resistantance of the alloy. The results reveal that the hardness of the alloying layer is improved from HV85 of the ZM5 substrate to HV250. The microstructure of the alloying layer was observed by OM （optical microscope） and SEM （scanning electron microscope）,and composition distribution in the alloying layer was determined by EPMA. Meanwhile,the corrosion behavior of the alloying layer was analyzed by the potentiodynamic polarization curve. The results show that the microstructure of alloying layer is refined,and Al and Mn element concentration is higher than that in the substrate. Self-corrosion potential and corrosion current density in the alloying layer are significantly decreased,which are responsible for the improvement of the corrosion resistance.关键词：High-energy Micro-arc Alloying;Magnesium Alloy;Microstructure;Corrosion
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发布时间：2023-12-18 - 摘要：Microstructure features and dynamic softening behavior of aluminum sheet for easy-open can during hot deformation were analyzed by hot deformation simulator and TEM （transmission electron microscope）. The results show that dynamic recovery occurs at a low temperature with a strain rate of 0.1s-1,and dynamic re-crystallization appears obviously with temperature higher than 723K. Dynamic re-crystallization can be observed in the sheet with a low strain rate at 673K,when strain rate is higher than 0.1s-1,with increasing in strain rate,softening behavior is characterized by the combination of dynamic recovery and dynamic re-crystallization. However,it is characterized by geometry dynamic re-crystallization with strain rate more than 5.0s-1.
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发布时间：2023-12-18 - 摘要：High Mn-containing ZA35 alloy was prepared by spraying forming combining with hot squeezing casting at 320℃. Effects of varied squeezing ratios on microstructure and mechanical properties of the alloy were investigated. The results reveal that uniformly fine microstructure can be observed as a result of effectively restraining the precipitation of coarse Mn-rich phase in ZA-3.5Mn alloy during spraying forming. Subsequently,the as-deposited alloy can realize desirable compactness at a lower squeezing ratio during hot squeezing process,exhibiting excellent mechanical properties at room temperature.关键词：ZA35 Alloy;Spraying Forming;Squeezing Ratio
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发布时间：2023-12-18 -
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- 摘要：Based on the computational fluid dynamics （CFD）,the preparation process of semi-solid slurry by twin-screw was simulated to understand the velocity field and stress field in process of preparation,meanwhile,the role of twin-screw in shearing and stirring slurry was approached. The results reveal that twin-screw plays significant role in shearing and stirring slurry. In addition,stress that exhibits asymmetrical distribution at two sides of the screw is increased along the axial direction of the screw,which is possibly related to the rotating direction of screw.关键词：Semi-solid Slurry;Twin-screw;Numerical Simulation;CFD
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发布时间：2023-12-18 - 摘要：Numerical simulation based on phase field method was presented to describe solidification process of isothermal binary alloy with a forced convection. Effects of forced convection,supersaturation,coupling parameters and anisotropy values on dendritic growth were observed. The results indicate that crystal nuclei grows to an asymmetrical dendrite with a forced convection,in which upstream arm tip growth is promoted and downstream as well as perpendicular arm tip growth is inhibited,furthermore,perpendicular arm tip increasingly grows tiltedly towards the upstream direction with increasing in forced flow. In addition,with increasing in supersaturation,coupling parameters and anisotropy values,steady growth velocity of dendritic arm tip in upstream,perpendicular and down stream direction are increased.关键词：Phase Field Method;Forced Convection;Isothermal Alloy;Dendritic Growth;Steady Tip Velocity
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发布时间：2023-12-18 - 摘要：A4020 aluminum alloy piston was produced by thixo-forming method,in which alloy slurry was prepared by SIMA （strain induced melt activation）. Meanwhile,microstructure of the alloy before and after extrusion and microstructural evolution during reheating were observed by OM （optical microscope）. The results show that microstructure of the extruded alloy is converted from dendrite into streamline structure. In addition,the microstructure in process of reheating is evolved from irregular block structure into structure separation and into partial spheroidization finally into completely spheroidization.关键词：Semi-solid Casting;SIMA;Microstructure;A4020 Aluminum Alloy
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发布时间：2023-12-18 - 摘要：A new technology-thixoforging of metal/ceramic composites in pseudo-semi-solid state was presented based on the powder metallurgy technology combining with semi-solid metal forming process,which was used to prepare Al/Al2O3 composite cylinder parts. The thixo-forged cylinder parts exhibit compact structure and desirable bonding interface by OM （optical microscope） and mechanical properties testing. Compared with those of ones prepared by in-situ synthesis and by high temperature oxidization process,bending strength and fracture toughness of the parts thixo-forged are improved greatly. Improvement of mechanical properties of the parts is closely related to forming temperature and forming pressure. All above metioned results verify that the technology is feasible for preparing metal/ceramic composites.关键词：Al/Al2O3;Cylinder Parts;Pseudo-semi-solid
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发布时间：2023-12-18 - 摘要：Through optimizing the composition proportion based on experiment and analysis,AC7A alloy can meet the special mechanical property requirements of drawing engine for 300 km/h electric motive unit. The pollution of Fe and Si elements in alloy melt can be effectively controlled by conducting two-stage smelting. Pin-hole defect in the end cover can be greatly eliminated by smelting liquid alloy under coving flux and pouring. Inclusion and shrinkage porosity in the Al-Mg alloy end cover can be eliminated by adopting multi-step two-layer pouring system in low pressure casting.关键词：Al-Mg Alloy;AC7A Alloy;Low Pressure Casting;Electric Motive End Cover;High Ductility Materials
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发布时间：2023-12-18 - 摘要：Combination of vacuum and partial pressurization was adopted to eliminate the gas hole and shrinkage porosity in die casting automobile components. Four kinds of comparative experimental designs were presented including conventional die casting,vacuum die casting,partial pressurization die casting and combination of vacuum and partial pressurization. The results indicate that gas hole in die casting components can be eliminated by vacuum die casting,and shrinkage porosity in thick location of the castings can be solved,and both gas hole and shrinkage porosity can be relieved by combination of vacuum and partial pressurization method,which decrease the shrinkage porosity to 3.7% in the die casting components while shrinkage porosity in the conventional die casting components reaches 9.7%. In addition,the shrinkage porosity is decreased to 5.6% in partial pressurization die casting components.关键词：Die Casting;Vacuum;Partial Pressurization;Shrinkage Porosity;Gas Hole;Shrinkage Hole
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发布时间：2023-12-18 - 摘要：Small thin-walled frame stainless steel stirring propeller was produced by investment casting. By means of whole investment casting,through rational design and optimization of processing parameters,the casting defects in the propeller were decreased,raising the qualified rate of the castings.关键词：Stainless Steel;Stirring Propeller;Investment Casting;Processing Parameters
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发布时间：2023-12-18 - 摘要：Surface quality,hardness,cost and service life of the investment casting moulds were described,and a surface treatment method was optimized to be used for the practical mould. The relationship between mould surface quality and service life was presented by the experiment,and effects of surface change of mould during production on manufacturing precision and service life were expounded.关键词：Investment Casting Mould;Surface Treatment;Precision;Cost;Service Life
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发布时间：2023-12-18 -
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- 摘要：Effects of centrifugal forces on porosity rate and dimensional contraction rate of Ti-6Al-4V（TC4） alloy casting,which was prepared with vacuum graphite mould by vertical centrifugal casting,were investigated. The results reveal that with the increase of gravity coefficient,the porosity rate in the casting is decreased as a function of exponent,and the corresponding regression equation is presented. With increasing in rotating velocity from 0 to 210 r/min,dimensional contraction rate of the multi-step castings in length is significantly decreased. At a given pouring condition,the effects of casting mould on dimensional contraction rate are higher that those of centrifugal forces.关键词：TC4 Alloy;Vertical Centrifugal Casting;Centrifugal Forces;Porosity Rate;Dimensional Contraction Rate
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发布时间：2023-12-18 -
- 摘要：Technological properties and the peeling ability of water-base bauxite coating for EPC were examined. Crack easily occurs in the corner of patterns with bauxite coating after drying,resulting in the difficulty of peeling off from the castings as a result of the adhesion with coating after pouring liquid steel. The crack resistance of the coating layer can be greatly improved by introducing organic fiber A into ingredient of the coating. With only 1% organic fiber A addition,crack in the corner of the pattern can be obviously eliminated,and the coating behavior and strength are improved,however,with the content of organic fiber A more than 1.5%,uneven coating thickness can be observed as a result of easily flow down in process of brushing. The peeling behavior of coating after poured can be improved with adding a metal oxide B which could accelerate sintering,where with 4% 6% addition,coating exhibits desirable peeling behavior,so smooth castings surface can be observed. However,with metal oxide B content more than 8%,surface of the castings is adhered by a layer powder with occurrence of sand burning.关键词：Bauxite Coating for EPC;Pulp;Fe2O3;Crack Resistance;Peeling Behavior
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发布时间：2023-12-18 - 摘要：Based on the principle of downward continuous unidirectional solidification in the preparation of thin-walled copper tube,the physical and mathematical models of one-dimensional steady heat transfer for temperature field were established by analytical method. The effects of main parameters on the whole temperature field and solid-liquid interface and its mechanism were comparatively analyzed by combining calculated results with experimental data. The reasonable parameters were calculated under the condition of the highest casting speed in the limitation of existing processing parameters.关键词：Continuous Unidirectional Solidification;Temperature Field;Numerical Simulation
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发布时间：2023-12-18 - 摘要：Microstructure near oscillation marks （OSM） on 304L stainless steel continuous casting billets was observed by optical microscope （OM）,SEM （scanning electron microscope） and EDS （energy dispersive spectrometer）. A new type of morphology that is fusing-overflow-type OSM and two types of surface segregation in which one occurs at the bottom of the depression-type OSM,and the other occurs at the end of the overflow region above the hook origin line were observed. The EDS results reveal that the main segregation elements are Si,Mn and Ni,and the segregation rates are 1.11.6,1.3 and 1.11.2,respectively. It is concluded that the formation of fusing-overflow-type OSM and surface segregation are closely related to the temperature variation in initial solidification region,the deformation of solidifying meniscus,and the oscillation of mould.关键词：Continuous Casting;Stainless Steel;Initial Solidification;Oscillation Mark;Surface Segregation
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发布时间：2023-12-18 - 摘要：By introducing high gravity into combustion synthesis,the Al2O3/ZrO2 （4Y） eutectic composite ceramic large bulk plates were prepared. The XRD analysis shows that the ceramic plates are composed of α-Al2O3,t-Al2O3 and m-ZrO2 phase under high gravity. SEM observation reveals that with increasing in high gravity,eutectic colony embedded by t-Al2O3 fiber is transformed from cellular structure into rod-like one,in which volumetric fraction and length-diameter ratio of eutectic colony are increased gradually. Relative density,the Vickers hardness and fracture toughness of the composite ceramics are increased with increasing in high gravity,and maximum values reach 97.8%,18.7GPa and 15.6MPa·m1/2,respectively,at 225g. High fracture toughness of the ceramics is attributed to the coupled effects of crack-deflection and crack-bridging toughening by rod-like eutectic colony with transformation toughening and micro-crack toughening by the fine spherically-shaped tetragonal ZrO2 crystals at inter-colony regions.关键词：Al2O3/ZrO2 （4Y）;Eutectic Composite Ceramics;Combustion Synthesis;High Gravity;Toughening
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发布时间：2023-12-18 - 摘要：Crystallized microstructure of slowly solidified Cu52.5Ti30Zr11.5Ni6 bulk amorphous alloy was analyzed by XRD （X-ray diffraction） and TEM （transmission electron microscope）. It is found that there exists Cu-Ti2-Cu10Zr7,Cu3Ti-CuZr,Cu3Ti-Cu10Zr7-CuZr eutectic structure in the alloy system,which shows that the deep eutectic point of the amorphous alloy is composed of many low element eutectic reactions. Moreover,short-rang ordering clusters in the melt with configuration similar to that of Cu10Zr compound may be greatly contributed to the glass forming ability of the tested bulk amorphous alloy.关键词：Bulk Amorphous Alloy;Solidification;Eutectic Structure
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发布时间：2023-12-18 - 摘要：Effects of different Al contents on microstructure and mechanical properties of AZ series magnesium alloys were investigated. The results reveal that with increasing in Al content,numbers of Mg17Al12 phase distributed into α-Mg phase are increased with more continuous distribution in microstructure of Mg alloy,however,with 8% Al content,the α-Mg phase is isolated by the network Mg17Al12 phase. The mechanical properties of the alloy are closely related to the microstructure characteristics of α-Mg phase and Mg17Al12 phase. AZ71 magnesium alloy exhibits the best mechanical properties among three types of alloys. As-cast tensile strength,yield strength and elongation of the AZ71 alloy reach 211.63MPa,109.84MPa and 7.20%,respectively,and after solid solution treatment,tensile strength,yield strength and elongation reach 235.98MPa,122.12MPa and 14.72%,respectively. The distribution of brittle Mg17Al12 phase greatly affects crack propagation in tensile samples. The fracture morphologies of all AZ series alloys are characterized by brittle fracture.关键词：Magnesium Alloy;Al Content;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Effects of processing parameters on zinc-immersion effects in pretreatment process and of current density on Al plating layer in electroplating process were analyzed for Magnesium alloy. The surface and fracture morphologies of zinc-immersion layer and electroplating layer on the surface of the alloy were observed by SEM （scanning electron microscope） and EDS （energy dispersive spectrum）. Based on analyses of mechanical properties and composition,the pretreatment sketch of magnesium alloy and current density in subsequent electroplating process were designed. The results indicate that Al-plating layer with desirable bonding and high purity as well as uniformly compact structure on surface of Mg alloy can be obtained in ZnSO4-K4P2O7 solution for 7 min at 75℃,and with 3.54.1 A/dm2 during electroplating process.关键词：Magnesium Alloy;Zinc-immersion;Current Density;Electroplating
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发布时间：2023-12-18 - 摘要：Micro-pore foam aluminum was prepared by vacuum infiltration,and effects of different process on infiltrated length were approached theoretically. The results indicate that the hollow micro-balls pretreated by water and yttrium nitrate,respectively,the infiltrated length is greatly increased with increasing in diameters of the micro-balls,and it is drastically raised with increasing in pouring temperature of aluminum alloy,preheating temperature of micro-balls and mould,however,it is decreased with increasing in cavity section diameters. In addition,infiltrated length is improved with exerting mechanical vibration on the cavity.关键词：Composite Foam Aluminum;Hollow Micro-ball;Vacuum Infiltration;Technology
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发布时间：2023-12-18 - 摘要：Microstructure and mechanical properties of as-extruded Mg-（69） Al-Zn alloys were investigated by OM （optical microscope）,tensile testing and SEM （scanning electron microscope）. The results indicate that coarse dendrite in as-cast alloy is transformed into fine equiaxed grain in as-extruded ones. With increasing in Al content,tensile strength,hardness and grain size are increased,however,elongation is firstly increased and then decreased. Tensile strength,yield strength and elongation of AZ91 magnesium alloy reach 336.7MPa,245.3MPa and 17.1%,respectively,showing the most desirable comprehensive properties. Fracture morphology of Mg-（69）Al-Zn alloys is characterized by quasi-cleavage crack. Properties of the alloys can be improved with appropriate Al contents,however,crack tendency can be enhanced as a result of creation of Mg17Al12 phase with excessive Al addition.关键词：Mg-（69）Al-Zn Alloys;Al Content;Microstructure;Properties;Fracture Characteristics
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发布时间：2023-12-18 - 摘要：Taking commercial Ti and Al powders as reactants,Al3Ti powders were fabricated by sintering directly. Meanwhile,effects of Ti/Al molar ratio and sintering temperature on fabrication of pure Al3Ti powder were investigated. The results reveal that finer Al3Ti powder can be prepared with a higher Al/Ti molar ratio of 1∶2.5 by sintering directly compared with the theoretical value of 1∶3,so it is concluded that there exists Ti nucleus in Al3Ti powder prepared by sintering directly. The SEM observation and EDS analysis verify the presence of Ti nucleus in the Al3Ti particle.关键词：Reactive Sintering;Al3Ti Powder;Mechanical Milling
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发布时间：2023-12-18 - 摘要：Al-4Ti-B master alloy and Al-10Sr master alloy were prepared in condition of air,ice-water and liquid nitrogen. The refinement and modification effects of Al-4Ti-B and Al-10Sr master alloys at different cooling ways on the A356 alloy were comparatively analyzed. The results reveal that desirable refinement and modification effects on the A356 aluminum alloy can be observed by modification with liquid nitrogen treatment Al-4Ti-B and Al-10Sr master alloy,in which α-Al phase is converted into fine equiaxed grain with occurrence of spheroidized refining eutectic phase and the more uniformly distribution in the α-Al phase.关键词：Al-4Ti-B Master Alloy;Al-10Sr Master Alloy;Cooling Way;Microstructure
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发布时间：2023-12-18 - 摘要：Formation mechanism of wedge twins in AZ61 magnesium alloy during aging was investigated by OM （optical microscope）,TEM （transmission electron microscope） and EDS （energy dispersive spectrometer）,and effects of aging treatment on mechanical properties of the alloy were described. It is found that formation of wedge twins is attributed to the existence of large amounts of plate-like substructure in the alloy and proper Al atom concentration gradient in the grain. The yield strength ,tensile strength and elongation of the alloy are increased from 88.79 MPa,189.73MPa,6.93%,in as-cast state respectively,to 109.18MPa,250.03MPa,9.40%,in aged state,respectively,greatly improving the strength and ductility.关键词：AZ61 Magnesium Alloy;Aging;Twins;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Mg-6.1Li,Mg-8.2 Li and Mg-10.8Li,alloy ingots were prepared by melting in cast-iron crucible and casting in copper mould under the coverage of lithium chloride and lithium fluoride （LiCl:LiF=3:1） and the protection of argon,obtaining desirable ingot microstructure. Chemical reaction thermodynamic analysis reveals that graphite and magnesia are unsuitable as tool materials for melting and casting Mg-Li alloy,while cast iron,low carbon steel,Mo,copper and silicon carbide are suitable as tool materials. Thermodynamic analysis is basically consistent with the experimental results and relevant literatures.关键词：Mg-Li Alloy;Melting-casting;Microstructure;Thermodynamic Analysis;Chemical Reaction
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发布时间：2023-12-18 - 摘要：Cu-0.32Cr-1.82Fe,Cu-0.33Cr and Cu-1.87Fe alloys were prepared by vacuum melting,subsequently,the alloy ingots were treated by solution plus aging and solution-cold deformation-aging. Aging characteristics of three alloys were investigated by XRD （X-ray diffraction）,hardness and electrical conductivity measurements as well as lattice parameters measurement. It is found that although Cr and Fe addition can greatly improve the hardness of the alloy,it plays somewhat role in electrical conductivity of the alloy. The micro-hardness and electrical conductivity of Cu-0.32Cr-1.82Fe alloy reach 215HV and 31.9MS/m after solution treatment at 1000℃ for 2 hours and 80% cold deformation and aging at 480℃ for 1 hours.关键词：Cu-Fe-Cr Alloy;Alloying;Precipitation Strengthening;Microhardness;Electrical Conductivity
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发布时间：2023-12-18 - 摘要：Micro-hardness,electric conductivity and wear resistance of aged Cu-Cr-Zr alloy prepared by in-situ synthesis were examined. The results reveal that compared with that of initial samples,electric conductivity of 80% cold deformed alloy is increased approximately 100%,furthermore,with increasing in deformation rate,the electric conductivity of the alloy is increased. After aged at 500℃ for the cold deformed alloy,electric conductivity is obviously affected,however,change of hardness is absent. Tribological behavior is characterized by adhesive abrasion under current free while it is abrasive abrasion under current conditions.关键词：Cu-Cr-Zr Alloy;Aging;Micro-Hardness;Electrical Conductivity;Wear Mechanism
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发布时间：2023-12-18 - 摘要：Nickel bleached gold alloys were the dominant materials of white karat gold,which was widely used in jewelry production. Aiming at problems of nickel while karat white gold alloys in production and application were described such as nickel allergy,bad color,showing magnetic,bad cold working performance,stress corrosion cracking and casting defects,and origination of the problems were approached. The countermeasures were presented.关键词：Jewelry;Nickel Bleached;Gold Alloys
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发布时间：2023-12-18 -
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