Development of brazing foils to join monocrystalline tungsten alloys with ODS-EUROFER steel

Results on rapidly solidified filter metals for brazing W with W and monocrystalline W with EUROFER steel (FS) are presented. Rapidly quenched powder-type filler metals based on Ti-bal-V-Cr-Be were developed to braze polycrystalline W with monocrystalline W. In addition, Febal Ta-Ge-Si-B-Pd alloys were developed to braze monocrystalline W with FS for helium gas cooled divertors and plasma-facing components. The W to FS brazed joints were fabricated under vacuum at 1150 degrees C, using a Ta spacer of 0.1 mm in thickness to account for the different thermal expansions. The monocrystalline tungsten as well as the related brazed joints withstood 30 cycles between 750 degrees C/20 min and air cooling/3-5 min. (c) 2007 Elsevier B.V. All rights reserved.