Mechanical properties of superconducting rods for current leads prepared by unidirectional solidification

In this study, YBCO superconducting rods with Pt (0.3 wt%) and Ag2O (10 wt%) were grown at various pulling rates in order to obtain different microstructures such as single domained, cellular and blocky by using the unidirectional solidification method for investigation of the inter-relationships between the microstructure, superconducting performance and mechanical properties. The morphologies of the structures were changed from single domained to blocky through the cellular structure with increasing the pulling rate. The cell spacing decreases with increasing the pulling rate. On the other hand, the mechanical strength increases with increasing of the pulling rate in the region of the cellular structure. From these results, the reason for the improvement of mechanical strength seems to be due to the effect of the grain boundaries. Furthermore, the high critical current values were attained in the sample with the cellular structure