Properties of stabilized MgB<sub>2</sub>composite wire with Ti barrier

Kòváč, Pavol; Hušek, I; Melíšek, T; Holubek, T.

doi:10.1088/0953-2048/20/8/008

Cited by 36 publications

(31 citation statements)

References 17 publications

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“…Nb or Ti). Inter-diffusion was observed at Ti/Cu and NbTi/Cu interface of MgB 2 wires [6][7][8]. The strongest interface and temperature dependent interaction have been observed between the copper stabilizer and titanium barrier.…”

Section: Introductionmentioning

confidence: 99%

Stability of multi-core MgB2/Ti/Cu/SS wires

et al. 2011

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Stability of 19-filaments MgB 2 /Ti/Cu/SS wires carrying the transport currents has been examined. Properties of two identical wires annealed at 600 o C/2.5 h and 800 o C/0.5 h were compared. It was found that annealing conditions influence not only the current carrying capacity of MgB 2 filaments but also affect the inter-diffusion at Ti/Cu and Cu/SS interfaces, which is worsening the electrical and thermal conductivities of composite elements. Consequently, differences in wire's resistances and I-V quenches were measured, which are correlating well with experimentally estimated minimum quench energy and normal zone propagation velocity.

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Section: Introductionmentioning

confidence: 99%

Stability of multi-core MgB2/Ti/Cu/SS wires

et al. 2011

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“…The copper coatings enable the soldering. [14], which reports minor anisotropy originated from the grain orientation due to the flattening of the wire, but in our sample, the aspect ratio was close to one. The measurements and the computed values, based on the function with the optimized parameters, are summarized in figure 4.…”

Section: Experimental and Fitting Examplesmentioning

confidence: 41%

Low field critical current density of titanium sheathed magnesium diboride wires

Rostila

Grasso

Demenčík

et al. 2010

J. Phys.: Conf. Ser.

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Low field critical current density of titanium sheathed magnesium diboride wires (MgB2) is replacing some of the conventional superconductors due to its low cost and availability in kilometer lengths. MgB2 has also been considered for AC applications. In order to model the AC losses and the critical currents of the applications, intrinsic Jc(B)-dependence is an important factor also at low fields. In this work Jc(B)-dependence of an MgB2 sample is extracted from the standard in field voltage-current measurements. The proposed method is applied to a non magnetic titanium sheathed sample at 16 and 20 K and a simple formula for Jc(B) aligns with the measurements. In the fitting process, the critical current distribution inside the wire is numerically simulated in order to take the self field of the sample into account. Moreover, the same formula aligns with measurements of a different sample. These critical current measurements, performed at 4.2 K, were based on magnetization. In the self field computations, the superconducting cross section must be determined accurately. Therefore, we tailored an image processing tool for MgB2 wires to obtain the geometry from a photograph. IntroductionSince the superconductivity of magnesium diboride (MgB 2 ) was discovered in 2001 [1], the pursuit for high performance conductors started and currently these conductors are commercially available in kilometer lengths. The advantages of these wires are relatively low price and their suitability for cryocooled applications whose temperature range is between 12 to 30 K [2]. Therefore, they are expected to replace some of the conventional superconductors. The wires are becoming more attractive also for AC use, which is due to the higher operation temperature, and thus improved stability compared to LTS wires.In case of MgB 2 , there are plenty of suitable candidates for cheap matrix metals, which do not react with MgB 2 . However, they must also fulfill the mechanical, thermal, and electromagnetic requirements for a specific application. For AC applications, hysteretic materials, for example Iron and Nickel, are excluded. However, Titanium is a promising nonmagnetic sheath material, because of its mechanically excellent properties and the lightness [3,4].The AC losses depend on the intrinsic J c (B)-characteristics of superconductor [5]. Unlike in DC applications, the J c (B)-dependence has to be taken into account for the whole AC cycle, also at the low field values. In addition, J c (B)-curves provide valuable information on the quality of superconductor and on its pinning properties [6]. Therefore, we apply and develop

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“…Clearly, a darker region of reacted part of the filament can be seen next to the sheath. It is proposed, that elevated pressures and possibly also elevated HT temperatures [15] can lead to an enhanced diffusion between Ti in the sheath and B in the core. This phenomenon has been difficult to perceive in previously made samples because of the usage of more typical preparation conditions and HT temperatures.…”

Section: Resultsmentioning

confidence: 99%

“…The different precursor powder compositions are denoted as I, E and M, respectively. The Ti sheath is used because of its claimed inert properties and chemical stability in terms of reaction and diffusion at the interface [15]. As received MgB 2 (98% purity) powder was purchased from the company Alfa Aesar and used for the ex situ tapes.…”

Section: Methodsmentioning

confidence: 99%