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22 results on '"Ma, Qian"'

7. The β phase evolution in Ti-6Al-4V additively manufactured by laser metal deposition due to cyclic phase transformations

Author

Ma Qian, W. Hou, Xinyu Zhang, J.F. Gu, and Haozhang Zhong

Subjects
010302 applied physics, Materials science, Spectrometer, Mechanical Engineering, Analytical chemistry, Vanadium, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, Laser, 01 natural sciences, law.invention, chemistry, Mechanics of Materials, Transmission electron microscopy, law, Phase (matter), 0103 physical sciences, Thermal, General Materials Science, 0210 nano-technology, Layer (electronics)
Abstract

This paper investigates the evolution of the β phase in laser deposited Ti-6Al-4V via track of the cyclic phase transformation processes by dilatation experiments and characterization of the laser deposited microstructures by transmission electron microscopy (TEM) and an energy dispersive X-ray spectrometer (EDS). The formation temperature of the β phase in as-received mill-annealed Ti-6Al-4V decreased with increasing number of thermal cycles at the heating and cooling rates of 50 °C/s, while the vanadium (V) content in the β phase increased with decreasing β phase formation temperature. The distribution of the V content in the β phase in the laser deposited Ti-6Al-4V showed an increasing gradient from the top layer (i.e., the last deposited) to the fourth layer from the top, which is related to the thermal cycles and the formation temperature of the β phase. The formation mechanism of the β phase was discussed based on the experimental observations.

Published
2018

17. Microwave-assisted fabrication of titanium hollow spheres with tailored shell structures for various potential applications

Author

Shudong Luo, G. Stephani, Peng Yu, Ma Qian, H. Goehler, and Publica

Subjects
Materials science, Fabrication, Mechanical Engineering, chemistry.chemical_element, Sintering, Core (manufacturing), Condensed Matter Physics, chemistry.chemical_compound, chemistry, Mechanics of Materials, Slurry, General Materials Science, SPHERES, Polystyrene, Composite material, Microwave, Titanium
Abstract

Expanded polystyrene spheres are spray-coated with a Ti–7Ni-0.5B-binder slurry. The polystyrene core and binder are thermally removed and the resulting Ti-7Ni-0.5B shells are sintered by microwave radiation to produce titanium hollow spheres. Samples sintered at ≤1120 °C result in individual hollow spheres with permeable shells, while sintering at higher temperatures lead to an interconnected hollow-sphere structure with solid shells.

Published
2012

18. TEM and XRD characterisation of commercially pure α-Ti made by powder metallurgy and casting

Author

Ma Qian, Shudong Luo, Ming Yan, and G. B. Schaffer

Subjects
Diffraction, Materials science, Reflection high-energy electron diffraction, Mechanical Engineering, Condensed Matter Physics, Crystallography, Electron diffraction, Mechanics of Materials, Transmission electron microscopy, Powder metallurgy, General Materials Science, Selected area diffraction, Powder diffraction, Electron backscatter diffraction
Abstract

The hcp-structured alpha-Ti is one of the two basic phases (alpha-Ti and beta-Ti) materials. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyse the alpha-Ti phase in both as-sintered and as-cast alpha-Ti materials. The structure factor of the (0001) plane of the alpha-Ti phase is 0. No diffraction should thus occur from the (0001) plane of the alpha-Ti phase when characterised by either x-ray diffraction or electron diffraction. However, electron diffraction of the as-sintered alpha-Ti materials recorded unambiguous diffraction from the (0001) plane as well as (000 1) where l =2n +1 (n is integer). A detailed analysis has clarified that this is a result of double diffraction arising from the two strong neighbouring (10 (1) over bar0) and ((1) over bar 011) diffraction planes. The same phenomenon also occurred to the characterisation of as-cast alpha-Ti materials

Published
2012

22. Preparation and characterization of V2O5 macro-plates

Author

Zhou, Yuanyuan, Qiu, Zifeng, Lü, Mengkai, Zhang, Aiyu, and Ma, Qian

Subjects
*ELECTRON microscopy, *MICROSCOPY, *ELECTRON microscopic diagnosis, *ELECTRON microscopic immunocytochemistry
Abstract

Abstract: V2O5 macro-plates have been prepared using water/ethanol media. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The as-prepared V2O5 plates appear to be an orthorhombic structure, and they seem to be composed of strip-like V2O5 nanocrystals which appear to be parallel or perpendicular to each other. The band gap of the V2O5 macro-plates calculated from the optical absorption edge is about 3.4 eV, showing a strong blue shift compared to bulk V2O5. It is also found that the final shape of the V2O5 macro-plates strongly depends on the reaction conditions. The possible formation mechanism of the V2O5 macro-plates is discussed. [Copyright &y& Elsevier]

Published
2007
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