Fabrication high homogeneous NbTi alloy bars for ITER project

This paper reported the method for high homogeneous NbTi alloy bar. The triple VAR melting methods was used to fabricate the NbTi ingot. The Nb inclusion and oxidized were not found in this alloy. The hydraulic forging machine was used to improve the plasticity and reform the microstructure of Nb-47Ti bar. The SEM and X-RAY were used to research the segregation of Ti-rich in NbTi alloy. The forging flow line and Ti-rich speck which were main factors to affect the mechanical working properties of NbTi wire were solved by improving melting process. The microstructure of NbTi bar was also become very fine and homogeneous. The difference of chemical element Ti was only +/- 1%. The grain size of NbTi bar was smaller than 5 grade of ASTM. The NbTi wire for ITER which using this bar has already drawing to over 5000 meters long. The critical current density of this wire was higher than ITER standard. It is indicate that this NbTi bar could be used to NbTi wire for ITER project.