Influence of Preparation Process on Microstructure, Critical Current Density and Tc of MgB2/Fe/Cu Wires

摘要

The powder-in-tube MgB2 wires were prepared by high energy milling of Mg andB powder. The powder was not mechanically alloyed for 2h short milling time.However, the MgB2 grains in wires are very small (20 100nm) and resembled tothe dimple after post-heat treatment. The clear evidence for transcrystllinefracture is observed. It indicated that the grain connection was greatlyimproved and the fluxing pinning was significantly enhanced. Another point toview is no intermediate annealing was adopted during the whole rolling process.The influence of the post-heat treatment on the transport current density wasstudied. Despite the lower Tc of about 35K, the transport current densityreaches to 3X10E4A/cm2 at 15K and 3.5T for 700 sintered wires.