Mechanical properties of three types of high RRR niobium

Several future particle accelerator projects such as the International Linear Collider (ILC), the Rare Isotope Accelerator (RIA), Energy Recovery Linacs (ERL) and Free Electron Lasers (FEL) make use of Superconducting Radio Frequency (SRF) technology. The accelerating devices (cavities) are manufactured from bulk high purity (RRR) niobium and are being operated at cryogenic temperatures. Jefferson Lab has partnered with Reference Metals Company to optimize not only the properties of the RRR z niobium for high performance accelerating structures but also to reduce the manufacturing costs for the material and the devices. In this paper we present the mechanical properties of three types of high RRR niobium: (a) standard high RRR niobium presently used in the production of the cavities (b) niobium with 150, 500 and 1200 wt. ppm tantalum content and (c) high RRR single crystal niobium sliced directly from ingots.We will also briefly compare the performance of cavities made from these di