EDX and ion beam treatment studies of filamentary in situ MgB2 wires with Ti barrier

In situ SiC-doped filamentary MgB2 wires (with the diameter of 0.860 and 0.375 mm) with Cu stabilization separated by Ti barrier layers supported by outer SS sheath and annealed at 800 °C/0.5 h have been studied by combination of EDX analysis and ion beam selective etching. It was found that several Ti–Cu inter-metallic compounds were created by Cu–Ti interdiffusion and thus the barrier protection against Cu penetration into the superconducting filaments is limited. We showed an advantage of Ti use as the barrier material in our wires. Ti getters silicon out from the superconducting filament, what purges superconducting MgB2 from Si and creates an additional Si-rich layer in inner part of Ti barrier which prevents Cu diffusion more effectively.

► SiC-doped MgB2 wires with Ti barrier showed good Jc in magnetic field. ► Explanation why the Ti barrier fits to SiC-doped MgB2 filaments. ► Ti barrier getters Si from SiC-doped filaments and improve their properties. ► Si accumulated in an inner layer of Ti barrier protects filaments from Cu diffusion. ► Ion beam treatment helps to discover microstructure of complicated systems.