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Sn60Pb40 alloy powders were fabricated using the planar flow casting (PFC) atomization process. By using OM, SEM and EPMA, the characteristics of the morphologies and microstructures of the powders have been investigated. It is observed that the environment of ambient gas in the atomization box has great effects on the morphology of the alloy powders. The microstructures of Sn60Pb40 alloy powders produced by the PFC atomization process are completely composed of eutectic, which is made up of both oversaturated α solid solution and β solid solution. The microstructures of small size powders are extraordinarily undeveloped dendritic eutectic, in which the large majority of the α phase appears nearly spherical, evidently since the cooling rate is higher and the under-cooling is larger. As for the large size powders, since the cooling rate and undercooling are relatively low, lamellar α phase apparently increases in the eutectic microstructures of these powders, and there is even typical lamellar eutectic structure clearly observed in some micro-areas. After remelting tests by DTA, the microstructures of small size powders are transformed, which become composed of large crumby α phase and eutectic (α+β), while those of large size powders change into classical tin-lead structures of primary α phase plus lamellar eutectic (α+β). By studying the microstructures of tin-lead alloy powders, a model has been proposed to predict the microstructure formation of Sn60Pb40 alloy powders.

The influences of minor amounts of scandium on the microstructure and mechanical properties of as-cast ZA27 alloy have been experimentally investigated. The experimental results show that as far as the Sc addition is individually concerned, the refinement result of the as-cast ZA27 alloy with 0.5wt.%Sc addition is comparatively better. After alloying with minor amounts of Sc, the coarse dendrites of the ZA27 alloy are refined and transformed into the uniform and small equiaxed grain microstructure; also the eutectics among the grain boundaries become finer. The test results of mechanical properties show that the tensile strength and hardness of the as-cast ZA27 alloy containing 0.5wt.%Sc approach 495 MPa and 120.2 HB, increase by 28.5% and 33.1%, respectively, compared with those of the ZA27 alloy with no addition of Sc element, while the elongation of the alloy is improved to 7.6% from 2.7%. The SEM, EDAX and XRD analyses show that in the ZA27 alloy, the trace element Sc combines with Al to form the square Al3Sc phase particles, which serve as heterogeneous nuclei, facilitating the refinement of the microstructure and the improvement of the mechanical properties of the alloy.

Conventional planar flow casting (PFC) is one of rapid solidification processes for the fabrication of microcrystalline or amorphous ribbons. Based on the conventional PFC process, the planar flow casting atomization (PFCA) process has been developed, which is a new rapid solidification process for the production of metal powder directly from alloy melts. A prototype experimental apparatus was designed and manufactured. With the apparatus, Sn60Pb40 alloy solder powders were prepared, and the effects of the main technological parameters on the powder size distribution and morphology were experimentally studied. The experimental investigations indicate that the metal powders produced by the PFCA process can be classified by velocity; and fine spherical tin-lead alloy solder powders can be fabricated by adjusting the technical parameters. The new PFCA process has such features as high productivity and efficiency, low energy consumption, simple operation, short technological process, and large gross yield.

The influences of minor scandium and zirconium combination alloying on the as-cast microstructure and mechanical properties of Al-4Cu-1.5Mg alloy have been experimentally investigated. The experimental results show that when the minor elements of scandium and zirconium are simultaneously added into the Al-4Cu-1.5Mg alloy, the as-cast microstructure of the alloy is effectively modified and the grains of the alloy are greatly refined. The coarse dendrites in the microstructure of the alloy without Sc and Zr additions are refined to the uniform and fine equiaxed grains. As the additions of Sc and Zr are 0.4% and 0.2%, respectively, the tensile strength, yield strength and elongation of the alloy are relatively better, which are 275.0 MPa, 176.0 MPa and 8.0% respectively. The tensile strength is increased by 55.3%, and the elongation is nearly raised three times, compared with those of the alloy without Sc and Zr additions.

The influence of precipitated nanophases on the mechanical properties of Fe-based amorphous nanocrystalline alloys is an urgent issue to be explored. Two amorphous nanocrystalline alloys, i.e., (Fe0.9Ni0.1)86B14 and (Fe0.7Ni0.3)86B14 containing nanophase of the body-centered cubic and face-centered cubic structures, respectively, were selected to investigate the effect of the structure and volume fraction of nanophase on their mechanical properties. The results of nanoindentation experiments and the calculation of the volume and size of the shear transition zone reveal that the two alloys show different mechanical properties. When the volume fraction of the nanophase in (Fe0.9Ni0.1)86B14 is larger than 50%, the elastic modulus is increased suddenly and the volume and size of the shear transition zone is decreased dramatically, while no dramatic change occurs in (Fe0.7Ni0.3)86B14. Moreover, it was found by using molecular dynamics simulations that the main reason for these abnormal mechanical properties is the change of cluster type in the system due to the incorporation of nanophases with different structures. [ABSTRACT FROM AUTHOR]

Metallic glasses (MGs) with unique disordered atomic stacking structures exhibit excellent catalytic performance in wastewater treatment. The catalytic degradation of Orange II (AO II) aqueous solutions by four CuZr-based MG ribbons under such processing parameters as pH values, the dosage of ribbons, and temperature was investigated in this paper. The catalytic performance of the MG ribbons was characterized by using the degradation efficiency of the dye wastewater. The phase constituent, surface morphology, and chemical valence state of elements on the surface of MG ribbons before and after use were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the Cu46Zr42Al7Y5 MG ribbon has the best catalytic performance among the Cu46Zr47-xAl7Yx (x = 0, 1, 3, 5) MGs in the degradation process, and the dye in the wastewater can almost be completely decolorized within 60 min under the conditions of pH = 2, the dosage of ribbons being 1.8 g/L and water bath temperature of 313 K, with the degradation efficiency and chemical oxygen demand removal being 96.05% and 51.73%, respectively. Furthermore, the Cu46Zr42Al7Y5 MG ribbon still shows superior structural stability and degradation performance after repeated use, and the corrosion pits on the MG surface promote the physicochemical reaction between the wastewater and the ribbons. [ABSTRACT FROM AUTHOR]

Compared with the conventional casting process, digital pattern-less casting technology has many advantages such as good machining accuracy, a short processing cycle, and low production cost. It is a new rapid manufacturing technology for castings, integrated with CAD/CAM, casting, CNC machining and many other advanced technologies. With this digital casting technology, no pattern is needed for making molds; it is precise, flexible, and green. Usually, art castings have complex structures and are made in small batches or even made in a single-piece, especially for large-sized art castings. So it has the shortcomings of high cost, low efficiency and long time for making a pattern to produce art castings with the conventional casting processes. However, the digital pattern-less casting technology can be applied to fabricate art castings, since it can greatly shorten the manufacturing cycle and lower the production cost, thus having a very good prospect. In this study, based on the digital pattern-less casting technology, a plaque casting with artistic Chinese characters (a Chinese poem) was designed and manufactured, and the production process was demonstrated in detail. [ABSTRACT FROM AUTHOR]