Development of flexible filler ribbons by melt spinning for joining W to CuCrZr material for heat sink application

Abstract

This paper studies the use of the melt-spinning technique as an alternative filler fabrication route to obtain flexible 80Cu-20Ti ribbons, which presents flexible and adaptability properties to cover the divertor or first wall pipe in future fusion reactors. The results showed that best conditions are achieved using a 0.8 mm diameter of the nozzle and 30 m/s of the linear wheel-speed. This condition allows to change the microstructure of the fabricated ribbons giving rise to a lower Cu4Ti intermetallic phase formation enhancing the adaptability properties. Ribbon dimensions are high enough to cover the perimeter of the pipe. Best conditions were selected to use as filler material in W-CuCrZr brazed joints at 960 ◦C. The results showed the consecution of high metallic continuity interfaces. Besides, the selected brazing conditions did not cause any thermal effect in the W base material but caused a softening effect in the CuCrZr base material as a consequence of the coarsening process of the hardening precipitates.