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In order to investigate the effect of Nd, Gd composite modification and heat treatment process on the microstructure of Mg-8Al alloy, we analyzed the evolution behavior of Mg17Al12 closely related to mechanical properties of Mg alloys and rare earth phase. The microstructure of the specimens was characterized by metallographic microscope(OM), X-ray diffraction(XRD), scanning electron microscope(SEM)and transmission electron microscope(TEM), and the morphology and distribution of β-Mg17Al12 and Al2RE in Mg-8Al-1Nd-1Gd alloy during solution treatment at 420 ℃ and aging precipitation at 210 ℃ were observed. The experimental results show that the eutectic of Mg alloy after modification with Nd and Gd, β-Mg17Al12 transforms from a continuous network to a fine discontinuous island and Al2RE phase with good thermal stability is produced at the grain boundary. The phase decomposition process of eutectic β-Mg17Al12 in solution treatment is continuous network-discontinuous island-spherical particles. Finally, a supersaturated α-Mg solid solution is formed, while Al2RE phase do not change before and after heat treatment. Lamellar and acicular aging precipitation β-Mg17Al12 is distributed at the grain boundary and in the grain, respectively and the precipitated β-Mg17Al12 presents fine and dispersed distribution characteristics under the modification of Nd and Gd. [ABSTRACT FROM AUTHOR]

In order to study the effects of different sintering temperatures and heat treatment on the microstructure and properties of copper alloys, TiH2/Ti-doped Cu-Y2O3 composite powders were prepared by high-energy ball milling in this paper. After pressing-sintering-heat treatment, copper matrix composites were obtained.The microstructure of the composite was characterized by optical microscope（OM） and scanning electron microscope（SEM）, and Vickers hardness tester was used to test its hardness and eddy current conductivity tester. The results show that after high-energy ball milling and mixed powder, elements Y, Ti and O are evenly distributed on the surface of the composite powder. The sintering temperature and heat treatment has an important influence on the microstructure and properties of TiH2/Ti-doped Y2O3 reinforced copper-based composites. The TiH2/Ti-doped Y2O3 reinforced copper matrix composites achieved the excellent properties after sintering at 850 ℃ for 2 h and aging at 450 ℃ for 3 h. The electrical conductivity and hardness of TiH2-doped Y2O3 reinforced copper-based composites are 86.9% IACS and 70.1 HV respectively, and the electrical conductivity and hardness of Ti-doped Y2O3 reinforced copper-based composites are 76.8% IACS and 73.6 HV. [ABSTRACT FROM AUTHOR]

In order to study the effects of different sintering temperatures and heat treatment on the microstructure and properties of copper alloys, TiH2/Ti-doped Cu-Y2O3 composite powders were prepared by high-energy ball milling in this paper. After pressing-sintering-heat treatment, copper matrix composites were obtained.The microstructure of the composite was characterized by optical microscope（OM） and scanning electron microscope（SEM）, and Vickers hardness tester was used to test its hardness and eddy current conductivity tester. The results show that after high-energy ball milling and mixed powder, elements Y, Ti and O are evenly distributed on the surface of the composite powder. The sintering temperature and heat treatment has an important influence on the microstructure and properties of TiH2/Ti-doped Y2O3 reinforced copper-based composites. The TiH2/Ti-doped Y2O3 reinforced copper matrix composites achieved the excellent properties after sintering at 850 ℃ for 2 h and aging at 450 ℃ for 3 h. The electrical conductivity and hardness of TiH2-doped Y2O3 reinforced copper-based composites are 86.9% IACS and 70.1 HV respectively, and the electrical conductivity and hardness of Ti-doped Y2O3 reinforced copper-based composites are 76.8% IACS and 73.6 HV. [ABSTRACT FROM AUTHOR]

In order to lessen the effect of La-doped on the gas-sensing response of SnO2 powders, different La-doped SnO2 powders were prepared by sol-gel method, and the prepared SnO2 and La-doped SnO2 powders were characterized and analyzed by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscope (SEM), specific surface area and pore size tester ( BET) and X-ray diffractometer (XRD). The gas-sensing response of the samples were tested. The results show that La doping reduces the grain size of SnO2. With the increase of La doping, the gas-sensing response of La-doped SnO2 powders to ethanol increases first and then decreases. When the molar ratio of La/Sn is 0.25, the gas-sensing response of La-doped SnO2 powder to ethanol is the highest, 43. 5 % higher than that of pure SnO2 to ethanol. [ABSTRACT FROM AUTHOR]

Using SnCl2 • 2H2O and SnCL • 5H2O as tin source and polyvinylpyrrolidone (PVP) as polymer matrix, fibril was prepared by using simple and controllable electrostatic spinning technology, and SnO2 nanofibers were obtained after calcination. Scanning electron microscope (SEM), X-ray diffractometer (XRD) etc. were used to investigate the effect of PVP molecular weight and different tin sources on the morphological properties of SnO2 nanofibers, and the specific surface area and gas-sensing characteristics of SnO2 nanofibers were tested. The results show that the fiber precursor prepared by electrospinning can remove the polymer matrix and solvent after ca lei nation, and obtain pure tetragonal rutile SnO2 nanofibers, which show the characteristics of large specific surface area, high sensitivity and fast response speed. When PVP-K30 is used as high molecular matrix and SnCL4 • 5H2O is used as tin source, the prepared SnO2 nanofibers have uniform diameter, clear fiber, good orientation and better gas sensing characteristics. [ABSTRACT FROM AUTHOR]

Taking silicon as the basic negative electrode material of lithium-ion battery, and copper as the metallized modified material, the Cu/Si-based negative electrode materials for extruding 3D printing were prepared by physical method and chemical method. The microstructure and morphology of the Cu/Si-based negative electrode materials were characterized by X-ray diffractometer and scanning electron microscope, and its electrical properties and rheology were tested. It is found that there is no silicon-copper compound in the prepared composite, and the modification of copper mewllization can not ;1ffect the particl e size and morphology of silicon. Compared with the physical method, the copper particles in the Cu/ Si-based negative ink prepared by chemical method have more compact and un iform distrib ution, and the resistivity is as low as 0.11 kΩ • cm, which shows better conductivity. Moreover, when the shear rate is 1 mm• s-1, the viscosity is 102 Pa • s, the Cu/ Si-based negative ink shows good rheological property, which meets the requirements of 3D printing, and has a good application prospect. [ABSTRACT FROM AUTHOR]

In order to improve the dispersion of Ni and SnO2 in Ag matrix, Ag-Ni-SnO2 electrical contact materials were prepared by chemical deposition process. The physical properties and arc erosion resistance of the prepared Ag-Ni-SnO2 electrical contact materials were tested. The micro-structure and phase structure of the electrical contact materials before and after arc erosion were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy disperse spectroscopy (EDS) analysis. The results show that the microstructure of Ag-Ni-SnO2 electrical contact material is relatively uniform, and there is no single element segregation; the density, hardness and resistivity of the electrical contact material are 8.59 g/cm-3, 72.78 HV and 3.47μΩ/m, respectively; after the arc test, there is no obvious element separation on the surface of the materials, and part of Ni and SnO2 undergo oxidation reduction to produce NiO, which improves the arc ablation resistance of the Ag-Ni-nO2 electrical contact materials. [ABSTRACT FROM AUTHOR]