Papers by Keyword: Amorphous Phase

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Authors: Kai Chen Kuo, Pee Yew Lee, Jai Yush Yen
Abstract: In the current study, the amorphization behavior of mechanically alloyed Ni57Zr20Ti22Ge1 powder was examined in details. The conventional X-ray diffraction results confirm that the fully amorphous powders formed after 5 hours of milling. The thermal stability of the Ni57Zr20Ti22Ge1 amorphous powders was investigated by differential scanning calorimeter (DSC). As the results demonstrated, the glass transition temperature (Tg) and the crystallization temperature (Tx) are 761 K and 839 K, respectively. The supercooled liquid region ΔT is 78 K. The appearance of wide supercooled liquid region may be mainly due to the Ge additions which cause the increasing differences in atomic size of mechanically alloyed Ni57Zr20Ti22Ge1 powders.
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Authors: Dariusz Oleszak, Paul Hideo Shingu
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Authors: Hai Yang Bai, C. Michaelsen, W. Sinkler, Rüdiger Bormann
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Authors: Tripti Biswas, Srinivasa Ranganathan, Hisamichi Kimura
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Authors: Wei Kong Pang, It Meng Low, J.V. Hanna
Abstract: The use of secondary-ion mass spectrometry (SIMS), nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM) to detect the existence of amorphous silica in Ti3SiC2 oxidised at 500–1000°C is described. The formation of an amorphous SiO2 layer and its growth in thickness with temperature was monitored using dynamic SIMS. Results of NMR and TEM verify for the first time the direct evidence of amorphous silica formation during the oxidation of Ti3SiC2 at 1000°C.
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Authors: Jing Xu, Zheng Feng Zhao, Yan Wang
Abstract: In this paper, the effects of annealing treatment on the microstructure, thermal property and magnetic properties of mechanical alloyed FeSiBAlNiC and FeSiBAlNiCe amorphous high entropy alloys has been systematically investigated using X-ray diffraction, differential scanning calorimetry, field emission scanning electron microscopy and alternation gradient magnetometry. The results showed that annealing at different temperature range induced the pronounced microstructural evolution from the amorphous phase to a mixture of amorphous phase and intermetallics but without any formation of solid solutions. In addition, the thermal stability and heat resistance were enhanced with increasing the annealing temperature. Similarly, annealing treatment also had significant effect on the particle morphology, making the particles evolve from near-round shape to plate-like shape. Furthermore, subsequent annealing of W6-Ce amorphous HEAs enhanced the saturation magnetization (Ms) remarkably (from 0.6 emu/g of 140 h as-milled W6-Ce to 20.17 emu/g). But for the Ms values of the 140 h as-milled amorphous W6-C HEAs, annealing in different temperature range all exhibited a slightly decreased effect.
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Authors: Feng Yi, Xiao Lan Cai, Lei Zhou, Ming Jun Yu, Zheng Li, Qing Wei Jiang
Abstract: The Ti-48at%Al composite powder was synthesized by high energy ball milling. The properties of the composite particles, such as medium diameter,Phase ,microstructure and components, were respectively investigated . Results show that, the phase evolution process can be described by: Ti+ Al fcc Ti (Al),TiAl,TiAl3,Ti3AlTiAl3,Ti3Alamorphous phase. After milling 3 hours, Fcc Ti (Al) solid solution, TiAl, TiAl3, Ti3Al were found. After milling 9 hours, the amorphous phase of Ti - 48 at % Al were produced. The element distribution of the mechanically alloyed Ti-48at%Al powder was close to the initial design composition after 5 h milling, but this distribution was inhomogeneous. Medium diameter (D50) of Ti-48at%Al composite powder achieved the minimal size 9.56 μm after milling for 5hours.
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Authors: Guo Qing Gou, Nan Huang, Hui Chen, Da Li, Yan Liu, Hua Ji, Yong Hui Zhu, Gui Guo Wang, Jin Peng Yu
Abstract: Nanostructured WC-17Co coating was prepared by means of High Velocity Oxygen Flame (HVOF) technique. Characteristic of nano-structure of the coating was analyzed. The coating seems to be of lamination structure formed by fully or partially melted powder. It shows that the coating consists of melted and recrystallized zone, semi-molten zone and un-melted zone. Amorphous phase and nanocrystalline phase co-existed in the coating is due to the rapid heating and cooling during spraying. The nanostructured coating possesses excellent mechanical properties, which are closely related to the unique nanostructures existed in the coating.
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Authors: S. Kumaran, T. Srinivasa Rao
Abstract: The reported work is on Ti-48Al-12Nb-1Cr (at %) system synthesized in a high-energy planetary ball mill with optimized milling parameters. The synthesized powders are characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD) and Differential Thermal Analysis (DTA) in order to understand the structural and phase transformation. The results obtained from the above said studies show the particles refinement, formation of non-equilibrium structures, etc. High-energy ball milling results super saturation of Al and Nb in titanium matrix at 15 hrs of milling, nanocrystalline nature at 20 hrs and amorphous phase formation at 50 hrs of milling. Differential Thermal Analysis (DTA) and XRD scans of MA powder thermally treated at 750°C for 1 hr show the formation of TiAl and TiAl3 intermetallic compounds.
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