Influence of the Preparation Process on Microstructure, Critical Current Density and Tc of MgB2 Powder-In-Tube Wires

TL;DR

This paper investigates how different preparation processes affect the microstructure and superconducting properties of MgB2 wires, demonstrating improvements in in-situ methods to match ex-situ performance.

Contribution

It introduces an improved in-situ preparation approach for MgB2 wires and analyzes its microstructure and superconducting properties compared to ex-situ methods.

Findings

In-situ process can be optimized to match ex-situ wire performance.

Microstructure and stoichiometry significantly influence critical current density.

Improved in-situ wires show enhanced transport current capabilities.

Abstract

MgB2 wires and tapes suffer from a limitation of the transport current densities, especially at low field, due to an unsufficient thermal stabilization caused by hot spots from a non-homogeneous microstructure, the presence of secondary phases and voids. For the preparation of MgB2 wires and tapes two different precursor routes, using MgB2 (ex-situ process) or Mg + B (in-situ process) are applied. The in-situ approach allows variation of many parameters in the wire preparation and the improvement of this approach is the central topic of this paper. We present an improved in-situ approach, the characterization of the filament microstructure, effects from stoichiometry and the corresponding superconducting properties. The transport current capability of such in-situ wires could be improved to the level of the reference ex-situ wires.