最新刊期
卷 ， 期 10 ， 2007
- 摘要：Effects of power ultrasonic on microstructure and macro-structure of A356 alloy specimens were observed by treating Al melt with three kinds of power ultrasonic, and the mechanism was described. The results reveal that with the increase of power, the grain size is greatly refined as a result of fully broken of dendrite in the alloy melt, leading to the more compact structure in the alloy melt and the more smooth of the Al alloy specimens.关键词：Power Ultrasonic;A356 Alloy;Broken Crystal;Mechanism
- 2
- |
- 153
- |
- 3
发布时间：2023-12-18 - 摘要：Effects of SiC addition, stirring temperature and time on mechanical properties of SiCp/AZ61 magnesium matrix composites prepared by semi-solid stirring method have been examined by orthogonal testing. The results reveal that SiC addition has the most remarkable effects on the mechanical properties of the composites, then the stirring time and stirring temperature have. In the experimental conditions, the SiCp/AZ91 magnesium matrix composites with excellent performance can be prepared by adding 6% SiC （volume fraction） with stirring at 595 ℃ for 5 min.关键词：SiCp;Magnesium Matrix Composites;Semi-solid Stirring
- 2
- |
- 305
- |
- 5
发布时间：2023-12-18 - 摘要：AZ61 magnesium alloy wire with the diameters of 10 mm was fabricated by means of self-designed continuous rheo-extrusion equipment. Microstructure of the alloy can gradually be evolved from dendrites at the pouring entrance to the fine broken crystal, and to equiaxed and spherical grains at the extrusion zone due to the actions of kneading and shearing by the roll resulting in the sheared broken dendritic arm. During the extrusion forming process, solid phase structure in the central location has a slight deformation, while it has an evident deformation in the outside, and the ultra-fine grain structure can be generated in the meniscus. Prepared AZ61 magnesium alloy wire has desirable sectional microstructure, characterized by two-phase plastic flow with rational processing parameters.关键词：AZ61 Magnesium Alloy;Wire;Continuous Rheo-extrusion;Microstructure;Evolution Behaviors
- 2
- |
- 204
- |
- 1
发布时间：2023-12-18 - 摘要：Some kinds of protective coatings for induction cladding with cold compression processing were developed. The optimized chemical compositions in the coatings are 75% SiO2, 15%B2O3, 10% Al2O3 and 10% Al powder, MgO. The high-frequency induction cladding experiment verify that the cladding coating with 0.50.6 mm thick can be generated on the working side-surface, where the micro-hardness can be uniformly distributed, showing the role of oxidization resistant and alloy loss-proof of the protective coatings.关键词：Protective Coating;Induction Cladding with Cold Compression;Softening Temperature;Oxidation
- 2
- |
- 139
- |
- 4
发布时间：2023-12-18 - 摘要：Tensile-tensile high-cycle fatigue testing was conducted for die casting magnesium alloy AZ91D with adding 1% and 2% RE containing Ce at ambient temperature in the condition of stress ratio of 0.1 to obtain the fatigue curve. The fracture mechanism and origination of the magnesium alloy were described by observing fracture morphology. The results show that proper RE containing Ce addition has the positive effect on the improvement of high-cycle fatigue behavior of the AZ91D magnesium alloy, exhibiting desirable effects with 1% RE containing Ce addition.关键词：Die Cast Magnesium Alloy;RE Containing Ce;High-cycle Fatigue Behavior;SEM Analysis of Fracture
- 2
- |
- 242
- |
- 5
发布时间：2023-12-18 - 摘要：The effects of gravity convection perpendicular to growing surface on dendritic morphology growth of model alloy SCN-5% ethanol have been observed by a self-developed experimental apparatus, which has a growth room and an observation system. The results indicate that, compared with those in condition of the absence of gravity convection, the primary arm spacing can be increased and tip radius can be reduced with the increase of growth speed. Gravity convection can result in the rapid growth and more development of the second arm spacing at facing-flow side. The down-stream alternation of dendritic tip growth is attributed to the co-action of the Stokes force and gravity in the flow field.关键词：Gravity Convection;Directional Solidification;Primary Arm Spacing;Tip Radius
- 2
- |
- 219
- |
- 3
发布时间：2023-12-18 - 摘要：Effects of shake-out time and heat treatment on microstructure and properties of Cr28 cast iron after poured have been investigated. The results indicate that although the hardness and impact toughness of the Cr28 cast iron can be decreased with increasing cooling time in the sand mold, the Cr28 cast iron exhibits higher hardness and impact toughness with air cooling after cooling for 3 h in sand mold. The hardness and impact toughness of the cast iron are more than 56 and 4.5 J, respectively. The microstructure of Cr28 cast iron with varied shake-out time at air cooling is composed of martensite, residual austenite and different shape M7C3 carbide. The Cr28 cast iron can be improved by more than 60 in hardness and more than 2.8J in impact toughness after normalizing at 1040℃ and tempering at 100 ℃ with different shake-out time at air cooling.关键词：Cr28 Cast Iron;Shake-out Time;Heat Treatment;Microstructure;Properties
- 2
- |
- 147
- |
- 2
发布时间：2023-12-18 - 摘要：Effects of various cooling rates on solidification of the ZL114A alloy were investigated by experimentally analyzing multi-step ZL114A samples in low pressure casting. A nucleation model was established on the basis of experimental data, in which the thermal-kinetics parameters were provided. The results show that with the increase of cooling rate,all the liquidus temperature,nucleation temperarure and eutectic transformation temperature are decreased. A modified Cellar Automaton model coupled with FDM（finite differential method） was used to simulate the macro-solidification and microstructure evolution of the alloy. The microstructure at different positions of the engine for aerospace was predicted by the model, which was verified by the experimental value.关键词：Aluminum Alloy;Low Pressure Casting;Microstructure;Numerical Simulation
- 2
- |
- 419
- |
- 4
发布时间：2023-12-18 - 摘要：The volumetric principle of solid materials in plastic processing is no longer suitable for non-solid material processing. The volume of cavity and materials itself be contracted due to the cooling of materials itself, solidification as well as the distortion of the mold and the core under high temperature and high pressure in the non-solid forming processing such as liquid or semi-solid, the volume of cavity and materials itself after and before forming are varied apparently, which is called the phenomenon of inequality-volume of non-solid processing. In order to obtain the compact product, it is required that the volume of the materials after forming should be smaller than the volume of material poured into the cavity before processing, whose differential value is the potential compression volume of the materials so as to be compressed during processing. In other words, it is required that the initial volume of the cavity must be bigger than the volume of the metal occupied after forming, whose differential value is the sum of the squeezing volume of the extruded core and the exerted volume of the plunger, which is called the principle of inequality-volume of non-solid processing.关键词：Non-solid Processing;Inequality-volume;Mould Design;Technical Design;Quality Control
- 2
- |
- 71
- |
- 1
发布时间：2023-12-18 - 摘要：The formation mechanism of micro-porosity in aluminum alloy castings and the numerical models for predicting micro-porosity have been surveyed. The numerical models were categorized into four types, such as criteria function, Darcy’s law coupled with the conservation and continuity equation, hydrogen-diffusion-controlled pore growth models, microstructure coupled with pore models, based on the studied literatures. The advantages and limitation of each type of the models were described. Finally, the future development of advanced microporosity prediction models was expounded.关键词：Aluminum Alloy;Micro-porosity;Numerical Simulation
- 2
- |
- 308
- |
- 5
发布时间：2023-12-18 - 摘要：Semi-solid slurry of A356 alloy was prepared by a self-developed cooling slope method. The key processing parameters on the formation and evolution of non-dendritic microstructure in the semi-solid slurry were analyzed through observing the structure in the ingot prepared by the method. The results show that the optimized inclined angle is controlled at the 4060°with pouring at 620660℃. In addition, in the condition of water cooling, the desirable microstructure can be created in the slurry with applying different slope lengths at varied pouring temperatures. A given pouring length is beneficial to forming near spheroidal structure with pouring at low temperature. Meanwhile, the microstructure of the ingot can be evolved from dendrites into fine spheroid grain during cooling slope.关键词：Slurry Preparation;Cooling-slope-tube;A356 Aluminum Alloy;Processing Parameters;Microstructure
- 2
- |
- 199
- |
- 5
发布时间：2023-12-18 - 摘要：The microstructure and thermal plasticity of the semi-solid M2 high speed steel billets prepared by cooling slope method have been investigated. The results indicate that the microstructure and thermal plasticity of the high speed steel billet can be effectively improved by the semi-solid processing as a result of the elimination of serious carbide segregation in the billet and the transformation of developed dendrite into fine round equiaxed grain. Meanwhile, the eutectic carbide in the semi-solid billets is lower and thinner than that of ones in conventional billets, and it exhibits not the developed network structure in the conventional billets but discontinuous net structure, which can result in the improvement of the thermal plasticity and the more uniform distribution of carbide in the semi-solid billets after forged. However, the desirable thermal plasticity temperature interval still is 9001 200 ℃ in the condition of uniaxial stress.关键词：M2 High Speed Steel;Semi-solid;Eutectic Carbide;Thermal Plasticity
- 2
- |
- 95
- |
- 4
发布时间：2023-12-18 - 摘要：The microstructure and properties of AZ91 magnesium alloy treated by solid solution at （410±5） ℃ for 10 hours have been investigated by squeezing casting with squeezing ratio of 25∶1 at 330 ℃. The results reveal that the fine grain in the squeezed AZ91 magnesium alloy can be observed, in which the Mg17Al12 phase is dispersively distributed due to its broken state, and some look on stream-flow distribution. Meanwhile, the yield strength, tensile strength and elongation of squeezed casting AZ91 magnesium alloy are 210 MPa, 355 MPa and 18%, respectively, which are apparently superior to that of as-cast ones. The second phase Mg17Al12 has the important effects on the mechanical properties of the magnesium alloy.关键词：AZ91 Magnesium Alloy;Squeezing Casting;Microstructure;Properties
- 2
- |
- 606
- |
- 7
发布时间：2023-12-18 - 摘要：The flow morphology, turbulence and formation of gas hole in the aluminum alloy knuckle bracket in die casting were described by analyzing its structural features. Based on above analysis, the improved technological design was conducted, including strictly controlling the initial position and injecting angle as well as the thickness and lengh of ingate in mould cavity, and adopting smooth connection to relief the generation of turbulence of the liquid Al alloy in the in gate, and using longer diverter to ensure the fullness of the liquid Al alloy in the chamber as well as keeping the constant pouring temperature, and so on.关键词：Knuckle Bracket;Aluminum Alloy Castings;Flow Morphology;Turbulence;Gas Hole
- 2
- |
- 40
- |
- 1
发布时间：2023-12-18 - 摘要：The application of resin sand mold core, precoated sand mold core and hot pressing mold core to investment casting was introduced. The resin sand mold core has the advantages of making-convenient and low price, while the precoated sand mold core is suitable for the production of large investment casting, realizing the automation of core-making, and the hot pressing mold core has the features of precision size and high efficiency, especially suitable for the parts with complicated abnormal cavity. However, the same characteristics of three types mold core are as follows: using mold core to complete cavity to save the cost of mould making and to avoid the coating of cavity, so improving the quality of mold shell making and production efficiency.关键词：Resin Sand Mold Core;Precoated Sand Mold Core;Hot Pressing Mold Core
- 2
- |
- 257
- |
- 2
发布时间：2023-12-18 - 摘要：The high Mn steel sieve plate was successfully manufactured by lost foam casting,whose compositions meet the requirements of the Chinese Standard G/T5680-1998.The service life of the sieve plate can be improved by three to four times due to the substitution of ZGMn13-Cr2 for ZGMn13.Meanwhile,the production rate is greatly increased and the hot crack and cold crack in the sieve plate is eliminated by means of lost foam cating.The sieve plate has the higher quality with water cooling treatment.
- 2
- |
- 188
- |
- 1
发布时间：2023-12-18 -
Origination and Countermeasures of Trial-production Accident of Vertical Centrifugal Casting Machine
摘要：Aiming at the accident of breakout of mould top cover, the exerted force analysis of liquid metal was conducted based on flow static hydraulic principle, and strength of materials for screw bolt in mould top cover was checked. The results show that the direct origination is attributed to the low strength of screw bolt in top cover. Based on above analysis, it is suggested that the equipment safety should be enhanced, and safe operation procedures should be strictly made and implemented, and the equipment, mould and the fixed apparatus should be often checked and maintained.关键词：Vertical Centrifugal Casting;Accident Analysis;Safety Countermeasures- 2
- |
- 142
- |
- 2
发布时间：2023-12-18 - 摘要：The effects of the friction force between crystalline and surface of the ingot, cooling water pressure on the quality of the 5052 alloy ingot have been examined. The microstructure of the subsurface under different processing was observed by a polarized light microscope, and the chemical compositions of the segregation area were detected by EDAX. The results indicate that the liquid aluminum breakout can be effectively eliminated by polishing crystalline, applying lubricant oil on the crystalline wall and increasing cooling water pressure during pouring. In addition, the surface macro-segregation can be obviously restrained by increasing the cooling pressure up to 0.20 MPa.关键词：Al-Mg Alloy;Semi-continuous Casting;Breakout;Macro-segregation
- 2
- |
- 326
- |
- 5
发布时间：2023-12-18 - 摘要：The interface bonding behavior of steel/aluminum compound electric-conducting pole prepared by different technologies was investigated, which was employed in aluminum electrolytic processes. The results demonstrate that the steel/aluminum electric-conducting pole with metallurgical bonding interface can be produced with optimized processing parameters, in which the metallurgical bonding interface is composed of Fe2Al5 phase and FeAl3 phase. The interface electric resistance of the steel/aluminum compound poles is significantly lower than that of commercial ones.关键词：Electrolytic Aluminum;Steel/aluminum Compound Electric-conducting Pole;Interface Electric Resistance
- 2
- |
- 97
- |
- 4
发布时间：2023-12-18 - 摘要：A CeO2-modified aluminized coating has been fabricated by compound electro-deposition Ni-CeO2 and aluminization method on carbon steel. The corrosion resistance of the CeO2-modified aluminized coating in H2S solution was examined, and the microstructure of the coating was observed by SEM （scanning electron microscope）. The results indicate that the enriched CeO2 fine grain layer can be created in the CeO2-modified aluminized coating, obviously improving the corrosion resistance of the coating in H2S solution, which is 2.5 times higher than that of aluminized coating.关键词：CeO2;Modified Aluminized Coating;Compound Electro-deposition;Corrosion Resistance
- 2
- |
- 114
- |
- 0
发布时间：2023-12-18 - 摘要：Multi-layer spray depositing 7075/SiCp composites was densified by cyclic pressing. The effects of pressing temperatures, transverse deformation rate and reduction rate on the densification of the composites billets have been examined, and the mechanical properties of the cyclic pressed composites were tested. The results indicate that the spray deposited 7075/SiCp composites exhibit desirable metallurgical bonding with cyclic pressing at 420 ℃. All the transverse deformation rate of front six layer lattices in the composites can reach 15% and the average reduction rate of every lattice is 23.3% in minimum value and 37.9 in maximum value with the transverse deformation rate of 15% and reduction rate of 31%. The tensile strength of the composites after one cyclic pressing is greatly superior to that of the initial ones, exhibiting excellent densification effects of cyclic pressing.关键词：Multi-layer Spray Deposition;Cyclic Pressing;Densification
- 2
- |
- 65
- |
- 2
发布时间：2023-12-18 - 摘要：Microstructural evolution and oxidation resistance of hot dip aluminized layer on 20 steel were investigated during oxidization at 800 ℃ with different diffusion treatment. The results indicate that the oxidized rate at 800 ℃ is increased with extending time in the range of 2 to 6 hours when diffusion temperature is 750 ℃, while the oxidized rate is decreased with extending diffusion time in the range of 2 to 4 hours, and the minimum oxidized rate can be observed at 4 hours, then it is gradually increased with the diffusion time more than 4 hours when the diffusion temperature is 850 ℃. The desirable oxidation resistance of the hot dip aluminized layer can be obtained with the diffusion temperature of 900 ℃ for two hours. In addition, SEM observation reveals that the void in diffusion treated aluminized layer/substrate aggregates gradually into the linear crack parallel to surface, in which the internal oxidation occurs, during high temperature oxidation, which will evidently affects the oxidation resistance of hot dip aluminizing steel.关键词：Hot Dip Aluminizing Steel;Diffusion Technology;Oxidation Resistance;Internal Oxidation
- 2
- |
- 367
- |
- 2
发布时间：2023-12-18 - 摘要：A new apparatus was designed to improve the accuracy and reproducibility of alloy fluidity tested by spiral sample in the sand mould. Through automatic casting mechanism controlled by single-chip-microcomputer, the molten alloy is poured into the spirals at a scheduled temperature and constant pressure head. By the experimental analysis and comparing with the tranditional apparatus, the new apparatus show a great improvement in accuracy and reproducibility. The effects of pouring temperature on fluidity of aluminum alloys have been tested by the new improved apparatus, obtaining the relationship between fluidity and pouring temperature.关键词：Fluidity of Alloy;High Precision Apparatus;Spiral Sample
- 2
- |
- 414
- |
- 2
发布时间：2023-12-18 -
Influence of P and RE Modification on the Microstructure and Properties of Hypereutectic Al-Si Alloy
摘要：Influence of P and RE modification on the microstructure and mechanical properties of hypereutectic Al-21Si alloy have been investigated. The results reveal that the coarse bulky and strip primary Si in the alloy can be greatly refined, and eutectic Si is converted from coarse needle into fibre or short bar with modification, which can improve the mechanical properties of the alloy. With 0.08% P and 0.6% RE addition, compared with ones without modification, the tensile strength at room and high temperature of the alloy is increased from 236.2 MPa to 287. 6 MPa, and from 142.5 MPa to 210 MPa, increasing by 22% and 47%, respectively, and the elongation is increased by 56% and 42%, respectively, showing the desirable ambient and high temperature mechanical properties. The modification of primary Si is controlled by heterogeneous nucleation mechanism induced by AlP particles, and the modification of eutectic is resulted form the creation of twin grain from RE absorption. In addition, the strengthening mechanism of the alloy was described.关键词：Hypereutectic Al-21Si Alloy;P and RE Modification;Microstructure;Mechanical Properties;Modification Mechanism- 2
- |
- 152
- |
- 6
发布时间：2023-12-18 - 摘要：Effects of RE element La on microstructure and properties of ZL303 alloy have been investigated by means of optical microscope（OM） and mechanical measurements and orthogonal testing. The distribution of RE element La and its compound phase in the ZL 3030 alloy have been observed by SEM （scanning electron microscope）. The results reveal that microstructure of ZL303 can be evidently refined with La addition, in which black skeleton Mg2Si phase is converted into short-rod ones, and gray net-like AlFeMnSi is converted into skeleton ones. Orthogonal testing show that the tensile strength of ZL303 alloy with 1% La addition can be remarkably improved. Compared with that of ZL303 alloy, the tensile strength and elongation of Al-5Mg-Si-La alloy can be increased by 17% and by 120%, respectively, and the hardness can be slightly improved. Majority of La and its compound phase are distributed into the phase interface and grain boundary with minority of them into α-Al phase. In addition, the mechanism of La refining structure and improving mechanical properties of the ZL303 alloy was described.关键词：La;ZL303 Alloy;Microstructure;Properties
- 2
- |
- 151
- |
- 5
发布时间：2023-12-18 - 摘要：The ZL101 alloy was modified by means of Al-5Ti-1B and Al-9Sr master alloy. Compared with Sr modification, the Al-5Ti-1B and Al-9Sr master alloy composite modification can remarkably improve the comprehensive mechanical properties of the ZL101 alloy. The fracture SEM observation reveals that the grain size of eutectic Si in compositely modified alloy is greatly refined with more distribution, and the unit of fracture become smaller and the ductile zone is increased, which can be responsible for the improvement of mechanical properties of ZL101 alloy.关键词：ZL101 Alloy;Composite Modification;Mechanical Properties;Fracture-metallographics
- 2
- |
- 183
- |
- 3
发布时间：2023-12-18 - 摘要：The chemical composition of low Ni-Pb-Zn white brass BZn9-39-1 alloy was determined according to the alloying principle of Zn white brass. The property measurement show that the BZn9-39-1 alloy has bi-phase structure and light yellow, exhibiting excellent cold-hot working performance and mechanical properties as well as desirable corrosion resistance and turning ability, which can be suitable for the production of conventional glass frame.关键词：Low Ni-Pb-Zn White Brass;Technique;Properties
- 2
- |
- 225
- |
- 3
发布时间：2023-12-18 - 摘要：The microstructure evolution of a new titanium alloy Ti-29Nb-13Ta-4.6Zr prepared by vacuum casting was observed with aging treatment at 450 ℃. The results reveal that the microstructure in the alloy exhibits single under-cooled metastable β phase after solid solution treatment, while the mixed structure can be created in the alloy, which is composed of stable β phase dispersively distributed on αphase in grain and strip α phase as well as stable β phase adjacent to strip α phase in boundary, due to the transformation of metastable β phase into strip α phase during aging treatment.关键词：Biomedical Titanium Alloy;Aging Treatment;Microstructure Evolution
- 2
- |
- 184
- |
- 3
发布时间：2023-12-18 - 摘要：<正>四羊方尊（见下页）,商（公元前十七—-前十一世纪）晚期锡青铜高58.3cm,口边长52.4cm重34.5kg1938年湖南宁乡出土中国国家博物馆藏器腹由四头大卷角羊合成,羊首耸于器肩四角,尊腹四隅为羊的前胸,四羊相合形成尊腹,羊腿置子方形圈足上。羊首饰雷纹,背及前胸饰麟纹,两侧饰线条优美的长冠凤纹（见图1）。圈足饰龙纹。四羊方尊将器物造型与装饰巧妙地结合于一体。精丽刚劲的纹饰突显陶范制作匠师高超的雕刻技艺。
- 2
- |
- 253
- |
- 1
发布时间：2023-12-18
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0