نتایج جستجو برای: nanocrystalline composite
تعداد نتایج: 131664 فیلتر نتایج به سال:
In this work TiNi-based nanocrystalline alloys and composite were produced by mechanical alloying process with subsequent annealing at 750 ◦C for 0.5 h. Mechanical alloying was performed in a SPEX 8000 Mixer Mill. TiNi alloy was chemically modi ed by Ag elemental powder. Silver content equaled 5 wt%. X-ray di raction analyses revealed formation of TiNi main phase after annealing. Additionally, ...
A modified solution combustion approach was used for the first time in the preparation of nanosize zirconia toughened alumina (ZTA) composite. ZTA-1 with an average particle size of 37 nm was prepared using corresponding metal nitrates and urea. ZTA-2 with an average particle size of <10 nm was prepared by using mixture of fuels such as ammonium acetate, urea and glycine. The products formed we...
In this study, the microstructural, mechanical, adhesion, and hemocompatibility properties of nanocrystalline diamond coatings were examined. Microwave plasma chemical vapor deposition (MPCVD) was used to deposit nanocrystalline diamond coatings on silicon (100) substrates. The coating surface consisted of faceted nodules, which exhibited a relatively wide size distribution and an average size ...
The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline Pd x Au1- x thin films. This combination enables direct imaging of...
Macroscopic strain was hitherto considered a necessary corollary of deformation twinning in coarse-grained metals. Recently, twinning has been found to be a preeminent deformation mechanism in nanocrystalline face-centered-cubic (fcc) metals with medium-to-high stacking fault energies. Here we report a surprising discovery that the vast majority of deformation twins in nanocrystalline Al, Ni, a...
We demonstrate a simple strategy to either prevent or enhance hydroxide incorporation in nanocrystalline solid-state metathesis reaction products prepared in ambient environments. As an example, we show that ZnCO3 (smithsonite) or Zn₅(CO₃)₂(OH)₆ (hydrozincite) forms extremely rapidly, in less than two minutes, to form crystalline domains of 11 ± 2 nm and 6 ± 2 nm, respectively. The phase select...
Nanocrystalline silicon microwires are self-heated through single, large amplitude, and microsecond voltage pulses. Scanning electron micrographs show very smooth wire surfaces after the voltage pulse compared to as-fabricated nanocrystalline texture. Voltage-pulse induced self-heating leads to significant conductance improvement, suggesting crystallization of the wires. The minimum resistivity...
Storage of hydrogen is one of the key challenges in developing hydrogen economy. Magnesium hydride (MgH2) is an attractive candidate for solid-state hydrogen storage for on-board applications. In this study, 10 wt.% ZrB2 was co-milled with magnesium hydride at different milling times to produce nanocrystalline composite powder. The effect of milling time and additive on the hydrogen desorption...
The effect of coherency WC/Co phase boundaries on the fracture toughness of the nanocrystalline WC-Co cemented carbides is studied by MD simulation method. The simulation results show that the nanocrystalline WC-Co cemented carbides with coherency WC/Co phase boundaries has higher fracture toughness than that without coherency WC/Co phase boundaries. Moreover, the mechanism of why coherency WC/...
Nanocrystalline SnO2 thin films were successfully prepared using sol-gel dip coating technique. The starting precursor was used as tin chloride dihydrate (SnCl2.2H2O), ethanol and glycerin. As the prepared films were fired at 500 o C. These films were characterized using XRD, FESEM and TEM to known crystal structure, surface morphology and microstructure property. Elemental composition was stud...
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