Critical current density and mechanical performance of MgB2 superconductors prepared with different magnesium sources

Abstract

In this study, the critical current density and mechanical performance of MgB2 superconductors prepared using different magnesium sources (Mg and MgH2 with 99.9% and 96.5% purities, respectively) were analyzed. When the samples were characterized structurally and electrically, we found that the grain sizes were about 40 nm and transition temperature was around 30 K being lower than the literature. Critical current densities of all samples were calculated using Bean's model and our calculations yielded critical current density values higher than 106 A cm−2 in self-field. The highest critical transition temperature value belongs to M800 (Mg with 99.9% purity) sample and when the critical current density and transition temperature values of this sample are considered, this sample appears to have the potential for practical use. Vicker's microhardness measurements were performed and yield stress (Y), elastic modulus (E), brittleness (Bi), ductility (D) and fracture toughness (KIC) were calculated. All samples exhibited Indentation Size Effect (ISE) and microhardness measurements were compared with some microhardness models with were compatible with ISE behavior.