The influence of unidirectional copper alloying on the critical current density of MgB2
| Autor: | B A Glowacki, S K Chen |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Materials science
Annealing (metallurgy) Magnesium Kinetics Metals and Alloys Analytical chemistry Core sample chemistry.chemical_element Condensed Matter Physics Copper chemistry Pellet Materials Chemistry Ceramics and Composites Critical current Electrical and Electronic Engineering Argon atmosphere |
| Zdroj: | Superconductor Science and Technology. 19:116-121 |
| ISSN: | 1361-6668 0953-2048 |
| DOI: | 10.1088/0953-2048/19/1/019 |
| Popis: | Inward unidirectional copper diffusion into a pellet and the resulting alloying of Cu–Mg during in situ reaction of MgB2 were studied. The reaction between the copper and magnesium occurred at as low a temperature as 660 °C in a flowing argon atmosphere giving rise to the formation of a MgCu2 layer at the interface between the Cu and the MgB2. The kinetics of copper alloying in the core sample was much enhanced at 800 °C and above, as shown by energy dispersive x-ray analysis. Consequently, Jc was degraded drastically due to the decrease in the superconducting volume fraction. However, the alloying effect did not lower the Tc onset, but broadened the transition. A sharp Tc transition and Jc(6 K,4 T)~2 × 104 A cm−2 was achieved when annealing was conducted at the lower temperature of 750 °C. Direct comparison between the pure and copper alloyed samples shows that optimization of the heat treatment and hence Jc rests on the competing effects of phase formation and grain connectivity versus MgCu2 formation. |
| Databáze: | OpenAIRE |
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