A great attention has been paid to the research and development of nanostructured materials.The main preparation methods of ultrafine particles and nanostructured materials have been summarized. The applications of zone typical nanostructured materials have also been reviewed.The peculiar characteristics and properties. such as density, grain size, hardness, superplasticity,magnetic and catalytic properties have been discussed
The effects of Mg on the mechanical properties of 35CrNi3MoV steel has been studied in this paper. The results show that Mg has less effect on the tensile properties and hardness of the steel at room temperature, but a right amount of Mg improves impact and fracture toughness and decreases the fracture-transition temperature considerably due to inclusions modification, as well as prolongs the notch stress rupture life dramatically through strengthening grain boundary and modifying boundary carbides. There is an optimum Mg content, which is about 0.0030% in the experimental 35CrNi3MoV steel
Using the nickel welding wire, the effect of alloying elements on the chilling tendency of partial fusion zone (PFZ) of arc-welded ferritic ductile iron and the mechanical properties of weld metal have been systematically studied. On this basis a new nickel electrode for arc welding of ferritic ductile iron (QT400-17) is developed for the first time. The mechanical properties of its weld metal can match those of ferritic ductile iron. The width of carbide layer (WCL) in PFZ is significantly decreased, the welded joint has excellent machinability and the weid metal has high hot cracking resistance
High Al zinc-based alloys are widely used in industry for their good ambient temperature mechanical properties and damping capacity. With the rise of service temperature its damping property increases but mechanical property decreases greatly Here two ways-alloying and spray deposition technique were adopted to improve the service temperature limitation of the alloy ZA27 in an effort to develop a new functional material with high damping capacity and good elevated temperature mechanical property. The effects of addition of 5 wt pct of Si Qn the damping behaviour and elevated temperature creep resistance of alloy ZA27 were investigated. The damping capacity, as well as the relative dynamic modulus, was measured at frequency of 1,4 Hz over the 303 to 573 K. No peak phenomenon was observed for the specimens tested in the temperature range of interest. Experimental results indicated that the damping capacity of the deposited material was 2.8 times higher than that of the cast one at 305 K. The ball hardness values were used to evaluate the creep property and the creep activation energy of the deposited material is 3.9~5.7 kJ per mol higher than that of the as-cast one. The creep rate formuIation was also derived. Finally, the operative damping and creep mechanisms were discussed in the light of the data obtained from its characterization of microstructure, damping capacity and creep reslstance
A partial section of Ti-Ni-Si ternary system at 1100℃was constituted with Ni less than 50 at.pct. Twelve single phase areas were determined. The binary Ti3Si phase proposed to occur at 1100℃ was not found in our investigations. A phase with the composition of Ni2Ti9Si9 detected is possibly a new phase. No linear ternary compound was found. Some of these compounds show noticeable composition range
Al-4.5Cu-5Pb alloy was prepared by sand and chill casting. The same alloy was also spray deposited at a gas pressure of 1.6 MPa. The microstructural features exhibit a coarse to fine dendritic morphology for sand and chill cast alloys. Equiaxed grains were observed for spray fOrmed alloys. Wear testing employing a pin-on-disc type set-up, reveaIs considerably lower wear of spray deposited alloy compared to that of chill and sand cast alloys. The morphological features of wear track on specimen and debris indicated a mixed oxidative-cum-adhesive wear mechanisms for these alloys tested in the present investigation
The structure change of α2/γ interface in a Ti-45Al-10Nb alloy induced by hot deformation was investigated by conventional and high-resolution transmission eIectron microscopy. Two types of hot deformation induced special α2/γ intedeces, coherent intedeces with high density of ledges and semi-coherent α2/γ intedeces were found to be due to the absorption of mobile dislocations into the α2/γ inteface. For the misoriented semi-coherent α2/γ interfaces, the densities of dislocation ledges increase with the misoriented angle between (111)γ and (0001)α2 planes, and 1/3[111] Frank partial dislocations were involved in the dislocation ledges. Formation mechanism of these deformation-induced α2/γ interfaces was discussed to be related to the role of α2/γ interface5 adjusting the deformation as a dislocation sink absorbing the slipping dislocations in the γ phase
Magnetism and its dependence on annealing temperature for r.f. sputtered Co/Cu multilayers have been investigated. It was found that the easy magnetization axes of the films are paralIel to the substrate and the magnetic properties of both as-sputtered and annealed multilayers are isotropic in the film plane. The coercive field Hc is 4.8 kA/m and the ratio of remanence-tosaturation magnetization Mi/M is about 0.73 for as-sputtered samples. Both Hc and Mr/Ms increase with increasing annealing temperatures, especially when annealing temperatures are higher than 400℃. These experimental results can be interpreted using the ferromagnetic exchange coupling and the pinning theory of the coercivity
The microstructure and mechanical properties of a Ni3Al based Ni-Al-Mo superalloy-IC6 which possesses low impurity content and high density by spray deposition technique have been studied.The results indicate that the IC6 alloy has good tensile strength and elongation both at room and intermediate temperatures
A continuous cooling transformation (CCT) diagram of the simulated ADI weld metal has been developed by means of the Formastor-F diagram measurement apparatus, and revised by comparing with the actual welding. Finally the revised diagram was used to determine the welding technology
Hoppressed Si3N4/SiC platelet composites had been investigated with respect to their microstructure and mechanical properties. The results indicate that Vickers hardness, elastic modulus and fracture toughness of the composites were increased by the addition of SiC platelet until the content up to 20 vol pct. A slight decrease in flexural Strength was measured at room temperature with increasing SiC platelet content. The high temperature flexural strength tests at 1150, 1250, and 1350℃ were conducted. It was found that the flexural strength at elevated temperature was degraded with the rising temperature, and the downward trend of flexural strength for the composite containing 10 vol. pct SiC platelet was less. The results indicate that SiC platelet had a positive influence on the high temperature strength. Effects of SiC platelet reinforcement were presented
Results on fracture toughness of natural apophyllite crystals when subjected to impact are presented. The morphology of the cracks and fracture has been studied. It is found that the crack formation does not show any anisotropic property and remains the same whatever may be the orientation of the crystal. The average values of the fracture toughness KC and brittleness index, as determined from measurements of crack length, are estimated to be 0.107 gμm-3/2and 4.19μm-1/2 respectively for the a(100) plane. The yield strength forα(100), p(111) and c(001) planes of apophyllite crystals for lower loads is 2250. 2160 and 1840 MPa and for higher loads is 1510, 1600 and 1430 MPa respectively
Transparent conductive cadmium indium oxide films (CdIn2O4) were prepared by r.f. reactive sputtering from Cd-In alloy targets under an Ar-O2 atmosphere. Electrical conductivity of the order of 105Ω-1.m-1 and the optical transmission as high as 94% are easily attained by postdeposition annealing treatment. The effects of oxygen concentration in the reactive gas mixture and post-deposition annealing treatment on the optical transmittance as well as optical parameters, such as refractive index (n), extinction coefficient (k), real part (ε') and imaginary part (ε") of the dielectric constant, were studied in the visible and near-infrared region. The highfrequency dielectric constant ε∞ the plasma frequency ωP, and the conduction band effective mass mc of different samples were also investigated
Commercial grain oriented electrical steels were made by cross shear rolling (CSR) with a chosen mismatch speed ratio 1.1. Original sheets of 0.75 mm thick, which had been produced by conventional cold rolling and intermediate annealing were rolled to thickness from 0.35 mm to 0.15 mm, and followed by industry annealing. The deformation texture and the magnetic properties were measured. Results indicate that: in the condition of the CSR, the deformation texture of rolled sheet is generally similar to that of conventional rolled sheet; for sheets with the thicknesses from 0.35 mm to 0.25 mm, favorable deformation textures, mainly consisting of {111} <112>, are also found at subsudece layers, which may help produce sharp Goss texture, and after the final annealing, the magnetic properties of sheets are not lower than that of conventional rolled sheets
A model for the size-dependent initial sintering temperature of ultrafine particles was established. The theoretical predictions for the size-dependent sintering temperatures of W, Ni and Ag ultrafine particles are consistent with available experimental evidence
Sintering of nanocrystalline alumina by microwave plasma has been studied. The relative density,microhardness of the samples with different grain sizes by microwave plasma and other sintering techniques have been compared
The effects of hydrogen on the mechanical properties at room temperature of a Ti3Al based alloy Ti-24Al-11Nb-3V-1Mo have been investigated. The results show a parabolic rate relationship between the average hydrogen concentration of the alloy at constant temperature and charging time. The mechanical properties (ultimate bending strength and deflection) decrease with increasing hydrogen content in the alloy. The fractographic feature indicates that the decrease of the mechanical properties is due to the crack nucleation and propagation at the hydride Ti3AIH
Rapidly solidified Al92.3Fe4.3V0.7Si1.7Mm1.0 alloy has been studied by positron lifetime spectroscopy and the variations on the intedecial defects with the annealing temperature were revealed by an analysis of the lifetime results. The intedece characteristics derived from the positron-lifetime results could be used to give a satisfactory interpretation of the dependence of mechanical properties on the annealing temperature
The effect of ageing on the microstructure, mechanical properties and shape memory effect (SME) in a newly developed Fe-24Mn-5Si-8Co-4Mo shape memory alloy has been studied. It was found that Fe2Mo particles precipitate during ageing and thereby increase hardness and strength of the alloy The SME of the alloy can be remarkably improved by ageing and a maximum SME can be obtained when aged at 873 K. When the ageing temperature is over 873 K, the SME decreases with increasing ageing temperature. The reason for the improvement of SME by ageing in the Fe-Mn-Si-Co-Mo alloy is discussed
The two-target optimization problem for high strength high fracture toughness steels has been investigated. An effective method for two-target optimization of multi-variable non-linear complicated system is developed by combining simulated annealing algorithm with artificial neural network
The effect of corrosion process on facilitating local plastic deformation for α-Ti in methanol has been investigated with the micro-multiplicative moire interferometer technique. The size of plastic zone and the plastic strain ahead of loaded notch have been measured. The results show that the anodic dissolution, or corrosion process itself can enhance the plastic zone and the plastic strain ahead of a loaded notch during stress corrosion of α-Ti in methanol solution
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