Forming properties and microstructure of Al-Cu alloy prepared by liquid-die forging

The Al-Cu wheel adopting the new Al alloy was prepared by the liquid-die forging,and the mechanical properties,composition distribution,microstructure and fracture behavior were investigated.The results showed that serious Cu segregation was found in the wheel specimen;the microstructure of the Al-Cu wheel was comprised of the casting microstructure and a small amount of the deformed microstructure;the best heat treatment and water quenching system were found to solution treated at(530±5)℃ for 4 h followed by(535±5)℃ for 24 h and aging treated at(155±5)℃ for 4 h;the fracture morphologies of the samples heated under T 6 and T 5-1 heat treatment showed flat,tough nest,and poor plastic characteristics;the fracture morphologies of the samples heated under T 4 heat treatment exhibited complete resilience,but no residual metallographic characteristic;the sample treated under T 4 protocol had the best elongation;the fracture failure was mainly due to the formation of the CuAl_(2)(θ)phases;and the fracture mechanism of the Al-Cu wheel was intergranular fracture.

The Synthesis and Film Forming Properties of Unsymmetrical Phthalocyanine Bearing One Crown Ether Void

The synthesis of phthalocyanines bearing one crown ether macrocycle and three alkoxyl chains is described. They form stable monolayers and can be employed for the preparation of multilayer films by the Langmuir-Blogett technique. The orientations of the molecules in the film were affected by alkali metal ions in the subphase. lt is suggested that a kind of 'sandwich' dimer was formed in the film induced by potassium ions

Changes in sulfur form during coal desulfurization with microwave:Effect on coal properties

The changes in sulfur form in coal were analyzed by sulfur K-XANES(K-edge X-ray absorption near edge structures) spectra before and after the coal microwave desulfurization in a Na OH solution. After the desulfurization, the pyritic sulfur content of coal decreased significantly from 53.6% to 39.2%, while the sulfate sulfur content increased from 17.3% to 34.6%. Only a small amount of thiophene sulfur(20.1–16.1%) was removed. Some sulfur-containing components were oxidized to sulfate sulfur. Under the optimum conditions, the ash content decreased, while the volatile content increased. The calorific value of coal slightly decreased with a slight variation in the amplitudes. The overall structure of coal did not change significantly based on Fourier transform infrared(FTIR) spectral analyses. Thus, the desulfurization of coal with microwave irradiation in a Na OH solution did not significantly change the properties of coal.

Effects of Processing Technologies on Mechanical Properties of SiC Particulate Reinforced Magnesium Matrix Composites

Mg matrix composites with SiC particles ranging from 5vol%-25vol% were prepared using stirring casting method. Die casting, squeezing casting, and extrusion were applied for inhibiting or eliminating the defects such as gas porosity and shrinkage void. Through die casting and squeezing casting, most of the defects in Mg matrix composites could be eliminated, but the mechanical properties were improved limitedly. On the other hand, after hot extrusion, not only most of the defects of as-cast composites ingots were eliminated, but also the mechanical properties were improved markedly. With the addition of SiC, the tensile strength, yield strength and elastic modulus of as extrusion SiCp/AZ61 composites increased remarkably, and the elongation decreased obviously.

Nanomechanical Properties of Amyloid Fibrils Formed in a Water Nanofilm on Mica Surface

The assessment of nanomechanical properties of a single amyloid fibril in a confined space provides important information for understanding the role of fibrils in a cell microenvironment. In this study, the structure and nanomechanical properties of different fibrils formed in water nanofilms on mica surface are carefully investigated by using the new atomic force microscopy imaging mode-peak force quantitative nanomechanics （PF-QNM）. We find that two types of fibrils with different morphologies are formed in water nanofilm on mica. The compression elasticities of these two types of fibrils are 3.9±0.9 and 2.5±0.6 GPa, respectively. The remarkable difference is possibly due to the structural discrepancy in two types of fibrils.

A STUDY ON THE STRUCTURE AND PROPERTIES OF POLYBUTYLALDEHYDE FORMED IN LOW TEMPERATURE PLASMA

The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed that the polymer formed in plasma is amorphous crosslinked polymer, and its backbone is made of carbon atoms. The surface energy of the polymer film is independent of the polymerization conditions. No addition reaction has taken place in the carbonyl group of butylaldehyde in the plasma condition. The result of the wettability measurements showed that the polymer film is generally hydrophobic and the surface energy of the film is about 41 dyn/cm, in which the dispersion force contribution is the majority. The electron diffraction proved that some crystal substance, even the single crystals were present in the polymer. X-ray diffraction also proved the presence of crystal and showed about 15% crystaUinity fraction.

Microstructure and Mechanical Properties of Two-phaseTiAl Alloys in Lamellar Form

In two-phase TiAl alloys, the lamellar structures are of special interest and importance since they are so common and persistent. not only under as-cast conditions but also after thermal treatment. However. the lamellar structures are still poor in ductility,although they are beneficial for toughness and high temperature strength. This article will review the recent progress made in understanding the basic mechanical properties of the γ and α2 phases which comprise the two-phase alloys in Iamellar form, and discuss how an improved balance of strength and ductillty in the lamellar form may be achieved

Draping Behavior of Carbon Non-Crimp Fabrics and Its Effects on Mechanical Performance of the Hemispherical Composites

In order to investigate the draping behavior of non-crimp fabrics（NCFs）, two types of carbon NCFs with tricot-chain stitches or chain stitches were formed on a hemispherical mould via a stretch forming process. The shear angle and forming defects of the fabrics were measured on the hemisphere, under different blank holder forces（BHFs）. The results showed that increasing BHF could enhance the shear angle slightly, reduce the asymmetry for the deformation of the fabrics, and change the main type of the process-induced defects. Besides, compression tests were performed on the corresponding composite components. By analyzing the change of fiber volume fraction and structural parameters of the textile reinforcements, the effects of draping behavior of NCFs on the mechanical performance of the composites were studied. The results reveal that draping process has distinguishable impacts on the mechanical properties of the final components, which is closely related to the stitching pattern of the NCFs.

Compressed glassy carbon:A novel form of carbon with previously unachievable property combinations

Subject Code:E02With the support of the National Natural Science Foundation of China,a collaborative team led by Profs.Zhao Zhisheng(赵智胜)and Tian Yongjun(田永君)from the State Key Laboratory of Metastable Materials Science and Technology,Yanshan University demonstrates a new form of carbon with

Deuteron form factors in a phenomenological approach

The electromagnetic form factors of the deuteron, particularly its quadrupole form factor, are studied with the help of a phenomenological Lagrangian approach where the vertex of the deuteron proton-neutron with D-state contribution is explicitly taken into account. The results show the importance of this contribution to the deuteron quadrupole form factor in the approach.