Effects of controlling grain growth mode on microstructures and properties of Cu foil

By means of direct current electrodeposition, Cu foil with columnar grain growth and equiaxed grain growth with different average grain sizes were prepared. Electron backscatter diffraction (EBSD), X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscope (TEM) were employed to elucidate the correlation between the microstructures and properties of Cu foil after a certain relaxation time under different grain growth methods. A remarkable preferential ratio of {220} orientation was exhibited in the columnar-grown copper. However, as the copper layer transitions to equiaxed grain growth, the superiority altered to {200} crystal orientation. This variability in grain orientation makes the copper layer profile of columnar crystal growth higher than that of equiaxed crystal formation. The twin boundary density in copper foil increases as the grain growth mode changes from columnar to equiaxed, and grain refinement is beneficial to increase the twin boundary density in the samples. And columnar crystal copper and equiaxed crystal copper show different twin characteristics. There are a few single-stage twin steps in columnar crystal copper and more multi-stage twin steps in equiaxed crystal copper. With an increase of twin boundary density, both the tensile strength and the ductility increase remarkably

A circular-polarization reconfigurable meng- shaped patch antenna

In this paper, we introduce a reconfigurable artistic patch antenna with unidirectional circular-polarization (CP) radiation. The novel geometry composed of a Chinese character Meng - shaped patch and dual L-shaped feeding probes that are connected to a PIN-diode-based switching circuit. The simulated and experimental results show that the proposed antenna achieves the operating bandwidth from 2.4 to 2.5 GHz that covers dynamically the 14 channels of IEEE 802.11/b/g/b/ax. By switching the L-probes, either left-handed CP or right-handed CP can be generated to cover different seven-channel blocks in order to enhance the channel efficiency. A broadside realized gain varying between 5-6 dBic and an efficiency of were recorded. The proposed antenna holds an overall dimension of 0.72 lambda(0)x0.72 lambda(0)x0.12 lambda(0) with an aperture efficiency of 59% at 2.45 GHz

Surface reinforcements of TA15 titanium alloy with laser induced Co base multiphase composites

© 2020 Elsevier Ltd Ultrafine particles (UPs)/amorphous phases (APs) reinforced composites was deposited on the TA15 titanium alloy via a laser cladding (LC) of the Co-Al-B4C-CeO2 mixed powders; a LC technique (the laser power 900 W, the scanning speed 2.5 mm/s) favored APs/UPs to be produced owing to the transient existence of the laser molten pool (laser pool), its COF was in a range of 0.390–0.425. Then, the monolayer graphene oxide sheets (MGOSs)/carbon nanotubes (CNTs) reinforced composites were formed on this LC fabricated coating by a mean of LC of Co-Al-B4C-CeO2-(MGOSs/CNTs). Noting that a laser beam irradiated on MGOSs/CNTs also the pre-melted powders, huge amounts of MGOSs/CNTs were melted but kept partial MGOSs/CNTs in the solid states; also lots of UPs were produced in the atomic arrangements of APs/MGOSs, considering that partial UPs could obtain large quantity of the energy from a laser beam, forming lattice distortions. Identification of the synthetic UPs and MGOSs/CNTs in such LC composites, more importantly an UPs’ effect, contributes the theoretical/experimental basis to improve quality of the laser 3D print fabricated composites