Mechanical properties of reinforced MgB2 wires

TL;DR

This study investigates how reinforcement materials and heat treatment affect the mechanical and superconducting properties of MgB2 wires and tapes under axial strain, relevant for their use in electrical devices.

Contribution

It provides new insights into the mechanical behavior and critical current response of reinforced MgB2 wires and tapes, highlighting the effects of stainless steel reinforcement and heat treatment.

Findings

Increased stainless steel reduces critical current in high magnetic fields.

Heat treatment significantly improves transport current levels.

Tape geometries have poorer mechanical properties than wires.

Abstract

For technical application in windings of coils, transformers or motors, a reinforcement of MgB2 wires and tapes is necessary to withstand applied stresses and strains and to avoid cracks in the filaments. Therefore, the response of the superconducting transport currents on applied axial strain in different magnetic background fields was investigated for differently stainless steel reinforced MgB2 wires, by means of an axial strain rig. Increased amounts of stainless steel in the sheath caused a stronger decrease of the critical currents in fields above 3 T as a consequence of a changed irreversibility field. Heat treated wires have a quite different mechanical behaviour compared to as-cold-worked wires, but an about 10 times higher transport current level. Tape geometries, having generally higher current carrying capabilities than wires, showed much poorer mechanical properties with a less effective filament precompression from the matrix.