Evolution of defects in titanium grade 2 under Ti2+ion irradiation

The complexity and diversity of microstructure involved in titanium alloysmakeit rather difficult to quantitatively describe defect evolution due to irradiation. This paper focusesondefect evolutions of commercially pure titanium grade 2 under Ti2+ ion irradiation considering the effect of dose (0.6 and 3 dpa), temperature (300°C and 430°C) and flux (15:1 ratio). An irradiation damage profile was predicted using SRIM software to obtain a homogeneous damage on at least 500 nm depth for TEM observations and simulated using JANNUS-Saclay facility. The details regarding the quantification methodologies of the defects from dark field images are provided, as are the origins of the associated uncertainties. In addition to a tangled dislocation network, presence of the -type and -component loops is observed. The latter was scarcely reported in the literature in the case of titanium alloys. At low temperature, the size distribution of the -type dislocation loops remained similar regardless of the dose and flux whereas these parameters have highly influence at 430°C. A widening of the size distribution and an increase of the threshold incubation dose (TID) was noted with the temperature. In the case of the -component loops, it was shown that the nucleation occurred in spite of the 0.6 dpa low dose

Gain Enhancement of Monopole Antenna using AMC Surface

A CPW rectangular-ring antenna over an Artificial Magnetic Conductor (AMC) is presented in this work. The AMC is a designed as a dual-band structure having an array of unit cells and operates at 2.45GHz and 5.20 GHz. A CPW antenna uses this dual-band AMC structures as a back-plane. Performance comparison is carried out with and without incorporation of AMC. The simulated and measured results show that the combination of the AMC reflector and the antenna provide directional properties at both frequency bands. It has been found that the antenna gain increases by about 5 dB

Miniaturized Concentric Hexagonal Fractal Rings Based Monopole Antenna for WLAN/WiMAX Application

In this paper a new antenna design technique is introduced in order to achieve tri-band operation as well as antenna miniaturization. The technique consists of using two concentric first-iterative hexagonal rings connected to each other as a radiating patch fed with a Y-shaped microstrip line. The proposed antenna operates at three frequency bands to cover 2.4/5.8 GHz WLAN and 3.5GHz WiMAX bands. The numerical analysis and simulation are carried out with CST MWS. The measured return losses of the proposed antenna show good performance and good agreement with the simulated results. Consequently the proposed antenna with compact size of 9.77 mm x 17 mm x 1.63 mm is well suited for wireless applications

Carbon content evolution in austenite during austenitization studied by in situ synchrotron X-ray diffraction of a hypoeutectoid steel

Using in situ high energy X-ray diffraction study of austenite formation in hypoeutectoid steel with three differ- ent initial microstructures (ferrite-pearlite, tempered martensite and bainite), the lattice parameters of ferrite, cementite and austenite are examined on heating at 0.25, 10 and 100 °C/s. The lattice parameters of ferrite, cementite and austenite do not vary linearly with the temperature, especially, in the temperature range where the austenitization takes place. For the austenite, it is suggested that the deviation from the linearity is mainly associated to the carbon content variation. Using Dyson and Holmes equation, the carbon content in austenite is evaluated for any moment of the austenite formation for each initial microstructure and all heating rates. For the ferrite-pearlite microstructure heated at 0.25 °C/s, the carbon content in austenite after complete cementite dissolution corresponds to that of pearlite. Moreover, a rapid decrease in carbon content in the austenite is observed during the first stage of the austenitization (simultaneous dissolution of ferrite and cementite) followed by a slow further decrease during the transformation of the remaining ferrite. The obtained results are discussed using thermodynamic calculations

An UWB-UHF semi-passive RFID System for localization and tracking applications

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Evolution of intermetallics, dispersoids and elevated-temperature properties at various Fe contents in Al-Mn-Mg 3004 alloys

Nowadays, great interests are rising on aluminum alloys for the applications at elevated temperature, driven by the automotive and aerospace industries requiring high strength, light weight and low cost engineering materials. As one of the most promising candidates, Al-Mn-Mg 3004 alloys have been found to possess considerably high mechanical properties and creep resistance at elevated temperature resulted from the precipitation of a large number of thermally stable dispersoids during heat treatment. In present work, the effect of Fe contents on the evolution of microstructure as well as high temperature properties of 3004 alloys has been investigated. Results show that the dominant intermetallic changes from α-Al(MnFe)Si at 0.1 wt. % Fe to Al6(MnFe) at both 0.3 and 0.6 wt. % Fe. In the Fe range of 0.1 to 0.6 wt. % studied, a significant improvement on mechanical properties at elevated temperature has been observed due to the precipitation of dispersoids, and the best combination of yield strength and creep resistance at 573K (300°C) is obtained in the 0.3% Fe alloy with finest size and highest volume fraction of dispersoids. The superior properties obtained at 573K (300°C) makes 3004 alloys more promising for high temperature applications. The relationship between the Fe content and the dispersoid precipitation as well as the materials properties has been discussed

A Breakdown Voltage Extraction Technique Using Numerical Modeling In Mos Structures

In this paper, the potential profile that is based on the numerical solution of the Poisson's equation can be used to determine the breakdown voltage of any MOS structures. To validate this work, a comparison between an experimental breakdown voltage and a calculated one. One of the important applications of this method is to make optimum designs to meet predetermined breakdown voltages