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In this paper, the attenuation coefficients of X-rays for a range of voltages (20-35) kV were studied for copper-based alloys (Cu + 0.05 AL + 0.03 Ti) according to the order (A1,A2,A3,A4,A5),by adding percentages of silver (X=1,2,3,4,5)% with two particle sizes (Nano) and (Micro) to the alloy (Cu92-x +5%Al +3%Ti+ Ag x) according to the orders (B1,B2,B3,B4,B5) and (C1,C2,C3,C4,C5) All alloys were sintered at (9000C) for a period of (4) hours. The results showed a direct relationship between the attenuation coefficient and the compression pressure. At the operating voltage (20Kv), the linear attenuation was increased (53.6%) and the mass attenuation was (53.8%), the hardness increased by (45%) and the porosity decreased by (18%) when comparing the results of Alloy (A1). with (A5), respectively, and it was also found that the relationship is direct between the attenuation coefficient and the percentages of silver addition, as it was noticed that the linear and mass attenuation coefficients increased by (34.5%) (34%) when comparing the results of (B1) with (B5), respectively, and the increase is By (33.9%) (33.5%) when comparing the results of (C1) alloys with (C5), the hardness has increased by (33.4%) (32.2%) when comparing the average values of alloy results from (B1) to (B5) and alloys from (C1) to (C5) and the porosity decreased by (37.6%) (31%), respectively. The attenuation coefficient is inversely proportional to the operating voltage, as it decreased by (20%) when comparing the results of voltages (20Kv) with (35Kv) for alloy (B5) and decreased by (26.4%) for alloy (C5). [ABSTRACT FROM AUTHOR]

Tungsten (W) plays a crucial role in the lifetime of the plasma-facing components of DEMO. In order to avoid oxidation, W-based alloys have been studied as alternatives to W. In this work, the Monte Carlo SRIM-2013 simulation program was used to calculate the nuclear stopping power, electronic stopping power, amount of target vacancies, displacements, replacement collisions, and total target damage of W, W-Cr-Si, W-Cr-Ti, and W-Cr-Y by hydrogen and helium ion bombardment. It is found that W is resistant to vacancies, atomic displacement, and total damage compared to W-based alloys. [ABSTRACT FROM AUTHOR]

A device based on smart alloys has been designed for use in machine building items, in particular, in nuclear engineering, for preventing anthropogenic and natural emergencies. The device breaks the electric circuit by cutting the electric wire bundle in case of an emergency increase in temperature above the permissible limit. [ABSTRACT FROM AUTHOR]

Low-angle ion scattering spectroscopy with Ne+ 11 keV ions was provided for the W-Cr-Y self-passivating metal alloy with reduced thermo-oxidation at different stages of vacuum pre-annealing. A comparison of the element's relative surface concentrations, obtained by the ions scattering spectroscopy, with the energy dispersive spectroscopy was provided. The simulation of the energy spectra of scattered Ne particles was performed by the SDTrimSP code. Simulated and experimental spectra were analyzed from the point of view of the accuracy of determining surface composition, as well as of existing limitations. Some patterns in the formation of the energy spectra for grazing-angle ion surface scattering case were analyzed. It was shown that impurities with low atomic number on the sample's surface may lead to the overestimation of the Cr concentration with this technique. The high sensitivity of the technique to moderate changes in elemental composition was noted. [ABSTRACT FROM AUTHOR]

W-Cr-Y smart alloys are potential material candidates for plasma facing components due to their protective behaviour during the loss-of-coolant accident (LOCA), while maintaining beneficial properties of W during the normal operation of the fusion power plant. During plasma exposure, the lighter alloying elements are preferentially sputtered at the surface, but in case of a LOCA, the plasma quenches and sputtering stops and diffusion of the alloying elements to the surface becomes intensive. The diffusion of Cr to the surface due to alloying elements (Y, Ti) yields a protective oxide layer stopping the sublimation of WO3. The phase stability and short-range ordering of ternary alloys in W-Cr-Y(Ti) systems has been investigated, using combination of Density Functional Theory (DFT) and Cluster Expansion (CE) methods with Monte-Carlo (MC) simulations. It has been found out from the DFT calculations, that all pairs in the W-Cr-Y system have positive values of the enthalpy of mixing, while most of the Cr-Ti and Ti-W binary structures have negative enthalpies of mixing. The shift in the short-range order as a function of temperature between Cr and W has been predicted as a result of Y addition in W-Cr-Y alloys compared to W70Cr30, by around 400 K towards lower temperatures. A strong tendency towards clustering of Y has been observed even at elevated temperatures (1800 K). The decrease of the order–disorder transition temperature (ODTT) as a result of the Y addition has been observed, while the addition of Ti has not shown any significant changes in the ordering of W-Cr-Ti alloys compared to W-Cr alloy. Our MC simulations showed that for the W70Cr29Y1 alloy the enthalpy of mixing (Hmix) value is positive in the whole analysed temperature range. Free energy of mixing above 1000 K has been calculated from the first nearest neighbours approximation for W70Cr29Y1 and W70Cr29Ti1 alloys. The results of the present investigations provide an insight enabling for optimizing chemical composition of materials for future plasma facing components.

A general phenomenological model of the kinetics of thermally induced structural phase transitions in multi-phase alloys is introduced for arbitrary numbers of lattice phases and transitions. The model is based on a system of ODEs yielding the temporal evolution of lattice phase fractions caused by temperature variation described by a heat balance equation. The kinetics of each transition are modeled by temperature rates of phase fractions rather than sigmoids, where an extra multiplicative parameter describing the shape of the transition rate curves is introduced. The model is applied to the electrical behavior of thin NiTi filaments by relating its resistivity to the relative proportions of three main structural phases, namely Martensite, Austenite and an intermediate phase, known as R-phase. The model yields resistivity time-series for successive heating/cooling cycles. Computer simulations are compared to previously published resistivity measurements on filaments self-heated by time-varying currents of various frequencies and passively heated samples. [ABSTRACT FROM AUTHOR]

• Joining smart alloys to EUROFER without interface layer was achieved by FAST. • W–Fe diffusion zone formed at the interface during joining. • Hardness decrease with increasing grain size was shown experimentally. • Chromium-carbides were detected around Cr-rich phases using STEM. Tungsten test is currently the baseline first-wall armor material for a future DEMOnstration power plant. Smart alloys, containing tungsten (W), 11.4 weight (wt) % chromium (Cr), and 0.6 wt% yttrium (Y), aim at achieving passive safety in case of air ingress into the vacuum vessel and a loss-of-coolant accident causing a temperature rise above 1200 K for weeks. In such a case, smart alloys suppress oxidation and sublimation of radioactive W. This publication summarizes several important properties of smart alloys: the suppression of oxidation, the hardness as a function of the microstructure, and potential carbide formation in the presence of carbon (C) impurities. Further, first results on joining them to the EUROFER by field-assisted sintering technology (FAST) without interface layer are presented. In literature, FAST is also known as spark plasma sintering (SPS). A stable joint with an tungsten–iron (W–Fe) diffusion layer of 100 nm at the interface was achieved. The joint survived several heat cycles to 873 K. [ABSTRACT FROM AUTHOR]

W-Cr-Y smart alloys are potential material candidates for plasma facing components due to their protective behaviour during the loss-of-coolant accident (LOCA), while maintaining beneficial properties of W during the normal operation of the fusion power plant. During plasma exposure, the lighter alloying elements are preferentially sputtered at the surface, but in case of a LOCA, the plasma quenches and sputtering stops and diffusion of the alloying elements to the surface becomes intensive. The diffusion of Cr to the surface due to alloying elements (Y, Ti) yields a protective oxide layer stopping the sublimation of WO 3 . The phase stability and short-range ordering of ternary alloys in W-Cr-Y(Ti) systems has been investigated, using combination of Density Functional Theory (DFT) and Cluster Expansion (CE) methods with Monte-Carlo (MC) simulations. It has been found out from the DFT calculations, that all pairs in the W-Cr-Y system have positive values of the enthalpy of mixing, while most of the Cr-Ti and Ti-W binary structures have negative enthalpies of mixing. The shift in the short-range order as a function of temperature between Cr and W has been predicted as a result of Y addition in W-Cr-Y alloys compared to W 70 Cr 30 , by around 400 K towards lower temperatures. A strong tendency towards clustering of Y has been observed even at elevated temperatures (1800 K). The decrease of the order–disorder transition temperature (ODTT) as a result of the Y addition has been observed, while the addition of Ti has not shown any significant changes in the ordering of W-Cr-Ti alloys compared to W-Cr alloy. Our MC simulations showed that for the W 70 Cr 29 Y 1 alloy the enthalpy of mixing (H m i x ) value is positive in the whole analysed temperature range. Free energy of mixing above 1000 K has been calculated from the first nearest neighbours approximation for W 70 Cr 29 Y 1 and W 70 Cr 29 Ti 1 alloys. The results of the present investigations provide an insight enabling for optimizing chemical composition of materials for future plasma facing components. [ABSTRACT FROM AUTHOR]

WCrY Smart Alloys are developed as first wall material of future fusion devices such as DEMO. They aim at behaving like pure W during plasma operation due to depletion of the alloying elements Cr and Y. The Cr concentration gradients induced by preferential plasma sputtering cause Cr-diffusion. The exposure of WCrY and W samples to pure D plasma, with a plasma ion energy of 220 eV , is simulated using the dynamic version of SDTrimSP. Cr-diffusion is included into the model. Simulation results are compared with experimental results. At sample temperatures of more than 600∘C and sputtering by D plus residual oxygen in the plasma ion flux, the Cr-transport to the surface leads to enhanced erosion for WCrY samples. A diffusion coefficient for Cr in WCrY of the order of 1 ⋅ 10 − 17 m 2 / s is determined. The suitability of WCrY as first wall armour and the influence of further effects, considering especially Cr-diffusion, is discussed. [ABSTRACT FROM AUTHOR]

In this paper, the experimental study and confirmation of the memristive behavior demonstrated by nanowires made of a smart alloy, namely NiTi, are presented. Further contribution to the characterization of the proposed novel NiTi memristor, included measurements in the ac domain, confirming the memristive nature of these NiTi wires/devices. These measurements included the device's response to triangular current excitation, as well as to pulse driving. In all cases, a study of the noise registered has taken place. According to the theory, since NiTi's memristive behavior is depended on its temperature, it is classified as an extended memristor. Unlabelled Image • Experimental characterization of NiTi smart alloy from the memristive point of view. • Study of NiTi electrical behavior in the ac domain. • Hysteretic resistivity changes according to the frequency of the applied current driving. • Memristive behavior manifested in both resistance to temperature and resistance to current dependencies. • NiTi smart alloy is classified as an extended memristor. [ABSTRACT FROM AUTHOR]