最新刊期
卷 ， 期 7 ， 2008
- 摘要：Low cycle fatigue behavior of Al-7Si-0.3Mg alloy was examined by mechanical fatigue testing with equivalent strain amplitude varied from 0.15% to 0.35%, and the dislocation evolution in the specimens was observed by TEM（transmission electron microscope）. The results indicate that the dislocation structure is closely dependent on strain amplitude, and the density of dislocation in failure specimens is increased with increasing in equivalent strain amplitude. Cyclic hardening can be found as a result of the dislocation interaction and particle pinning, and hardening region can been throughout the entire fatigue process with the strain amplitude more than 0.35%. Fatigue life is decreased with the increase of the equivalent strain amplitude,confirming to the equation of the Manson-Coffin.关键词：Cast Al Alloy;Low Cycle Fatigue;Dislocation
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发布时间：2023-12-18 - 摘要：In-situ （Al3Zr+Al2O3）/Al particulate reinforced aluminum matrix composites was synthesized by direct melt reaction method in Al-Zr（CO3） system with the reinforced particulate size of 0.53 μm. The apparent viscosity of the composites melt during synthesized process was measured with rotary cylinder method. The results indicate that apparent viscosity via time curves of the composites with 5% particle volumetric fraction belongs to a parabolic one, and keeps a constant value of 0.75 Pas after 25 min and is two times higher than that of 0.24 Pas of pure aluminum, which is attributed to the uniform and dispersive distribution of micron particulate in composites. Melt apparent viscosity of the composites with 15% particulate volumetric fraction is increased with the increase of time, and the particulate aggregation can be observed in the microstructure.
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发布时间：2023-12-18 - 摘要：Effects of the pressing passes on the microstructure and mechanical properties of AZ31 magnesium alloy during equal-channel angular prissing （ECAP） were investigated by X-ray diffraction and optical microscope.The results indicate that with inceasing in the pressing passes,elongation of the alloy is increased and the tensile strength is decreased as a result of the refinement of grain size.After 8 passes,grain size in the alloy is decreased from 120 μm to 9 μm,which is responsible for the deformation mode of α phase from twining in the first passes to the dislocation slip in the following passes.After pressing,the dispersive orientation of （0001） crystal face influences the tensile strength of alloy.Increase of elongation is attributed to the refinement effects and the activation of sliding plane.关键词：Magnesium Alloy;ECAP;Microstructure;Mechanical Properties
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发布时间：2023-12-18 -
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- 摘要：The Mg-9Gd-3Y-0.6Zn-0.5Zr magnesium alloy was treated by micro-arc oxidation in aluminite solution, and morphology and corrosion resistance of oxide coating at different electrolyte were investigated by SEM （scanning electron microscope）, X-ray and electrochemical testing. The results indicate that the corrosion resistance of the alloy can be greatly improved by MAO treatment. The optimized processing parameters as follows: NaAlO2 of 5 g/L, H2O2 of 10mL/L, KF of 6g/L, glycerine of 15 mL/L. The coating with uniform thickness consists of MgO, Al2O3 and MgAl2O4 as well as a little MgF2 phase.关键词：Micro-arc Oxidation;Magnesium Alloy;Aluminite
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发布时间：2023-12-18 - 摘要：Effects of processing parameters on microstructure of semi-solid slurry prepared by mechanical stirring were investigated. The optimized model of processing parameters in mechanical stirring was established by means of artificial neural network in which the solid fraction and solid phase size of the semi-solid structure are taken as input parameters and stirring velocity, stirring time, holding time and pouring temperature as output parameters based on orthogonal testing to prepare desirable semi-solid slurry. The optimized results are well in agreement with experimental ones. Therefore, the artificial neural network model can be used to optimize the processing of the slurring-making during the semi-solid forming. In addition, the model can be used for different slurry-making with altering input parameters.关键词：Artificial Neural Network;Semi-solid Microstructure;Semi-solid Slurry Making;Optimization
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发布时间：2023-12-18 - 摘要：Effects of simultaneous solidification and sequential solidification on quality of crankthrow shape parts were analyzed. The filling process of sequential solidification was simulated and compared with that from experimental results. The results show that the hot spot in crankthrow shape parts is effectively eliminated and the shrinkage porosity （hole） in the parts is decreased by controlling the sequence of solidification.关键词：Crankthrow Shape Parts;Sequential Solidification;Numerical Simulation
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发布时间：2023-12-18 - 摘要：The filling and solidifying processes of die casting magnesium alloy seat framework were visualized by a finite element method to predict the potential defect position in the seat framework. Based on simulated results, the design of gating system was optimized. The results show that the entrapped-gas and shrinkage porosity （hole） can be obviously decreased in magnesium alloy seat framework during die casting with optimized gating system, greatly improving the quality of die casting seat framework. Furthermore, the shortcomings of conventional die casting process and die design can be effectively relieved and the product period can be shortened greatly.
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发布时间：2023-12-18 - 摘要：The phase-field model based on the Tong and Bechemann model which couples the flow field was developed to simulate the effects of phase-field parameters on dendrite growth in microstructure of pure metal by the finite difference method （FDM）. The results show that the dendritic morphology obviously changes under the condition of convection, in which the branch of upper dendrite is the longest and that of down dendrite is the shortest and the length of the branch in horizontal direction is middle. The higher the undercooling rate is, the more development the side-branches in upper and in horizontal direction are; the larger the anisotropy parameters is, the thinner the branch of main dendrites is, and the smaller the second dendrite spacing is. In addition, the dendrite tip velocity is accelerated with the increase of convection velocity.关键词：Forced Convection;Thermal Noise;Side-branching;Phase-field Parameters
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发布时间：2023-12-18 - 摘要：Due to its high ratio of performance to price, multicrystalline silicon becomes the main photovoltaic materials. With low cost of the solar cells, it is significant to research and develop casting technology for multicrystalline silicon in solar cells. Origination, principle, advantages and disadvantages of the casting technologies were described for producing multicrystaline silicon ingot, ribbon silicon and film silicon, and the Si structure characteristics of the silicon prepared by different ways were expounded. New casting technologies for multicrystalline silicon were surveyed and prospected.关键词：Multicrystalline Silicon Ingot;Ribbon Silicon;Thin Film Silicon;Casting Technologies
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发布时间：2023-12-18 - 摘要：Effects of power ultrasonic parameters, including power, beginning temperature and end-shape of ultrasonic horn, on size and morphology of primary phase in semi-solid slurry have been investigated by applying power ultrasonic on the top of ingot. The results show that size and morphology of primary phase in semi-solid slurry are refined and spheroidized with increasing in ultrasonic power. The desirable size and morphology of primary phase can be observed with applying ultrasonic at 640 ℃. Meanwhile, end-shape of ultrasonic horn has obvious effects on the size and morphology of primary phase.关键词：A356 Alloy;Ultrasonic Power;Semi-solid;Primary Phase;Refinement;Spheroidization
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发布时间：2023-12-18 - 摘要：Microstructure and mechanical properties of rheo-die casting YL112 aluminum were investigated with die casting semi-solid billets prepared by self-developed LSPSF（low shearing pouring sloping forming） on DCC280 horizontal die casting machine. The results indicate that the die castings with desirable mechanical properties and little defects can be produced with rotating speed at 90 r/min and tilting angular of 25°as well as preheating at 550 ℃ for mould and pouring at 620 ℃. Furthermore, the mechanical properties of the die castings can be improved after heat treatment.关键词：YL112 Aluminum Alloy;Semi-solid Slurry;Rheo-die Casting;Mechanical Properties;Microstructure
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发布时间：2023-12-18 - 摘要：The pouring temperature, mould temperature, mould cooling and coating as well as pouring process of large Al-Si alloy piston in low pressure casting were described. The production efficiency and quality of Al-Si alloy with 300 mm in diameters can meet the production-volume requirements with pouring at 640 ℃ and filling at 0.025 MPa and 0.4 m/s as well as holding pressure at 0.220.25 MPa for 1314 min.关键词：Large Al-Si Piston;Low Pressure Casting;Temperature;Pouring Process
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发布时间：2023-12-18 - 摘要：In order to optimize the super slow speed （SSS） die casting process, effects of pouring temperature on mechanical properties of ADC12 magnesium alloy in SSS die casting were examined with a standard tensile testing specimen. The results show that the density of specimen in SSS die casting is higher than that in conventional die castings at various pouring temperatures. There exists a critical value for pouring temperature, which is closely related to die temperature and releasing agent. The desirable pouring temperature is 700 ℃ under the SSS condition, and the dendrite primary α-Al phase can be observed in the alloy at the pouring temperature. Compared with that in the alloy poured at higher temperature, the primary and secondary dendritic arm becomes shorter in the alloy, exhibiting better tensile properties.关键词：Aluminum Alloy;SSS;Die Casting;Pouring Temperature;Mechanical Properties;Microstructure
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发布时间：2023-12-18 - 摘要：Production of steel traverse plain double ear by indirectional casting was performed, in which the horizontal parting with four-part-in-mould was adopted. Liquid metal was squeezed to fill the cavity and solidify formation by bottom punch, and the castings were pulled by the top tray driving the knockout pin based on the upper punch impelling the top tray in the squeezing casting machine. In addition, the casting pole was formed by assembling side-oil cylinder to drive the side-pole. The mould was cooled by inner-set water-cooled copper pipe. Meanwhile, surface of the mould was coated the special coating to prevent a higher surface temperature on the mould as well as the impaction of liquid steel to the mould. The trial production verifies that the material rate can reach up to or more than 90% with 92.5% production sound rate in the squeezing casting. In addition, the castings with shrinkage porosity（hole） free and clean surface as well as sound microstructure can be successfully produced.
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发布时间：2023-12-18 - 摘要：The relationship of flow and solidification feeding was approached by analyzing filling process of liquid alloy in shell mold in investment casting. Effects of solidification ways on feeding were described. The feeding parameter value was given by analyzing characteristics of feeding system.关键词：Investment Casting;Solidification Feeding;Feeding Parameter Value
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发布时间：2023-12-18 - 摘要：The effects of processing parameters on surface recarburization of bainite wear-resistant steel castings with different shapes were examined in lost foam casting, and the mechanical properties of the castings were measured. Meanwhile, the effects of lost foam casting process on the mechanical properties of the castings were approached by comparing mechanical properties of rack in sand casting and in lost foam casting. The results reveal that the surface recarburization is closely related to the casting structures including shape and size, specific area, gating system, initial carbon content in molten steel as well as pattern density. The un-uniformity of surface recarburization in the castings is responsible for the heterogeneous mechanical properties in lost foam casting. Compared with that of ones in sand casting, the surface hardness of the castings in lost foam casting is obviously improved with good impact toughness.关键词：Lost Foam Casting;Cast Steel Castings;Surface Recarburization
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发布时间：2023-12-18 - 摘要：Solidification microstructure of eutectic Pb-61.9Sn alloy and hypereutectic Pb-80Sn alloy were compared in conventional condition and in stationary magnetic field. The results show that eutectic phase with apparent lamellar structure and narrowed eutectic spacing in Pb-61.0Sn alloy can be observed in stationary magnetic field, and there exists difference in bending at different region,while coarse microstructure with enlarged dendritic spacing in hypereutectic Pb-80Sn alloy can be observed in statioary magnetic field, in which the regular degree of dendrite is decreased with the fragmentation of dendrite arm. The Lorentz force in stationary magnetic field can restrain the flow of liquid alloy, leading to the generation of thermo-electromagnetic fluid effect in the solid-liquid interface, which is responsible for above mentioned phenomena.关键词：Stationary Magnetic Field;Melt Flow;Pb-Sn Alloy;Thermo-electric Current
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发布时间：2023-12-18 - 摘要：The synthesized system of TiB2 particles and TiB2/Cu composites fabrication process were described. The strengthening mechanism and electric conduction model of particle reinforced copper matrix composites as well as properties of TiB2/Cu composites fabricated by in-situ synthesization were surveyed.
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发布时间：2023-12-18 - 摘要：In-situ （Al2O3+Al3Zr）p/A356 composites have been synthesized successfully by the direct melt reaction method in the A356-ZrOCl2 system. With the help of X-ray diffraction （XRD）,scanning electron microscope （SEM）, it is found that the formed Al3Zr and Al2O3 particles are fine and well distributed in the matrix. The distribution of in-situ particles in remelted microstructure becomes more homogeneous with the spheroidization of particles with the increase of remelting temperature, however, partial particles can be coarsened with the remelting temperature more than 850 ℃. The optimium remelting temperature is 850 ℃. Meanwhile, with the increase of remelting times, the particles become finer and finer with more homogeneous distribution, however, the volumetric fraction of the particles can be dropped as a result of excessive remelting times, so the optimized remelting times is 5. Tensile testing reveal that tensile strength of the composites is improved with increasing in remelting temperature and in remelting times, however, it is deteriorated with remelting temperature more than 850℃ and remelting times more than 5.关键词：In-situ;Aluminum Matrix Composites;Solidification Microstructure;Mechanical Properties;Remelting Treatment
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发布时间：2023-12-18 - 摘要：Microstructure evolution of Zr and P compound modified Si/ZA27 composites during remelting at 475℃ was observed. The results show that microstructure of the composites modified by Zr and P is converted from developed dendrite into short-coarse dendrite with fine primary Si phase. The interconnected structure with a few or without boundaries is generated due to the growth of short-coarse dendrite, and is further formed irregular independent particle during eutectic phase melting, resulting in the spheroidization of the particles during partial remelting process. With the increase of heating time, the primary Si phase in the microstructure is spherodized with the decrease of Si phase size.关键词：Si/ZA27 Composites;Isothermal Heat Treatment;Modification
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发布时间：2023-12-18 - 摘要：The frictional stirring welding （FSW） for 2219-O aluminum alloy with 14mm in thickness was performed with varied welding parameters. The origination of typical flaw in FSW and effects of welding parameters and welding joint on the flaw were approached. The results indicate that compared with those of joint without defects, the yield strength, tensile strength and elongation of joint with void or tunnel defects are decreased by 11%, 32% and 153%, respectively. SEM observation reveals that the ductility-brittleness fracture morphology of the joint with defects can be observed, in which the rupture morphology of joint with tunnel defects exhibits dimple morphology with high oxygen content, while the ductility rupture in the joint without defects can be observed. In addition, the microhardness of joint with defects is lower than that of ones without defects. The mechanical properties of the joint with defects were deteriorated.关键词：FSW;2219-O Aluminum Alloy;Welding Defects;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Corrosion resistance of the ceramic coating formed by micro-arc oxidation （MAO） on a cast Al-14Si-5Cu-3Ni-1Mg alloy was examined with electrochemical methods as EIS and polarization curves, which was further validated by agravity. Effects of surface microstructure of ceramic coating on its corrosion resistance were observed by SEM （scanning electronic microscope）. The results reveal that MAO can remarkably improve the corrosion resistance of the aluminum alloy as a result of increasing the EIS and corrosion rate and decreasing the corrosion current. The improvement of corrosion resistance of the ceramic coating is closely dependent on the special microstructure and thickness, however, which is not always improved with the increase of thickness of the coating.关键词：Micro-arc Oxidation （MAO）;Al-14Si-5Cu-3Ni-1Mg Alloy;EIS;Polarization Curves;Corrosion
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发布时间：2023-12-18 - 摘要：With a constant power, frequency and depth of applying vibration, effects of power ultrasonic on nucleation and growth of grain in pure aluminum melt were described by applying ultrasonic at varied temperature ranges with a vibration-transfer tool rod. The results indicate that microstructure of the ultrasonic treated ingot can be significantly refined with average grain size at 77405 μm and increment of isotropic behavior, and the mechanical properties are improved by about 20%. The formation of equiaxed grain is closely dependent on the cavitation effects as a result of creation of amount of nuclei, while microstructure can be greatly refined with the homogeneous distribution of grain by acoustic stream effects as a result of restraining the growth of grain, however, nucleation in the aluminum melt is slightly related to the acoustic stream effects. Microstructure of the pure aluminum can be remarkably refined by cavitation effect combining acoustic stream agitation with increasing in temperature range of applying-vibration. In addition, the action area of power ultrasonic was approached based on solidification structure. It is found that proper applying-temperature is helpful for ultrasonic forming of industrial pure aluminum.关键词：Power Ultrasonic;Industrial Pure Aluminum;Solidification Structure;Cavitation;Acoustic Stream
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发布时间：2023-12-18 - 摘要：Effects of reverse voltage and oxidation time on oxide film formation, which is prepared by micro-arc oxidation in silicate systems on the AZ91D magnesium, have been investigated, and the phase constituent and cross-section as well as surface morphology of the oxidized film were observed by XRD （X-ray diffraction）, OM （optical microscope） and SEM （scanning electron microscope）. The results show that with increasing in reverse voltage, oxide film thickness and size of surface pore are gradually increased while the number of pores and micro-crack is decreased. With reverse voltage of 120 V, the ceramic coating with 157 μm in thickness can be obtained with the lowest pores and cracks. With extending oxidation time, the thickness of oxide film is increased and growth rate of coating is firstly increased then decreased. The oxide film showing desirable compaction is composed of MgO phase and Mg2SiO4 phase in the absence of Mg phase.关键词：Micro-arc Oxidation;Reverse Voltage;Oxidation Time;Ceramic Coating
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发布时间：2023-12-18 - 摘要：Microstructure and aging hardening behavior of Cu-Be alloy prepared by rapid solidification with single roller were investigated by XRD（X-ray diffraction）, ESEM and TEM. The results show that microstructure of the Cu-Be alloy is composed of supersaturated α phase, in which a large amount of nanoscale γ transition precipitated phase can be found, and fine island-shape β phase dispersed homogeneously in the matrix, exhibiting very fine equiaxed grain with size of 12μm. Meanwhile, the hardness of the alloy is directly related to the aging precipitation process.关键词：Rapid Solidification with Single Roller;Aging Hardening;Microstructure;Equiaxed Grain
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发布时间：2023-12-18 - 摘要：W-Cu contact materials containing different RE additives were prepared by powder metallurgy infiltration technology. Microstructure and properties of W-Cu contact materials containing different RE additives were compared, and the microstructure of the W-Cu alloys after arc erosion was observed by scanning electron microscope（SEM）. The results show that RE La element that is the desirable RE additive can make Cu phase continuously to distribute in W-Cu contact alloy. Compared with that of conventional W-Cu alloy, the arc erosion resistance of W-Cu-RE contact materials is obviously improved by about 30%, which is attributed to more easy vaporization of Cu under the action of arc from the contacts due to the La addition to take away lots of heat.关键词：W-Cu Alloy;Rare Earth;Electrical Contact Materials;Powder Metallurgy
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发布时间：2023-12-18 -
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