Microhardness as a tool for the filament density and metal sheath analysis in MgB₂/Fe/(Cu) wires

Abstract

Vickers microhardness measurements have been carried out on MgB2 composite wires deformed in iron sheaths. Because the local hardness of these composite materials can be simply measured, we can use these values as an indication of the density of the ceramic core. An array of microhardness measurements have been done for single- and multi-core MgB2 wires subjected to variable deformation and heat treatment processes. The results show how the fabrication process can affect the core density, and so the critical current density, as well as the properties of the metal sheath before and after sintering heat treatments.