THERMAL-STABILITY AND BRAZING CHARACTERISTICS OF ZR-BE BINARY AMORPHOUS FILLER METALS FOR ZIRCONIUM ALLOY

The thermal stability and brazing characteristics of Zi-Br binary amor phous alloys as a new filler metal for joining zirconium alloy were in vestigated in order to supersede physically vapor-deposited (PVD) bery llium used conventionally with many disadvantages. The Zr1-xBex (0.3 l ess than or equal to x less than or equal to 0.5) binary amorphous all oys were produced by melt-spinning method. In the selected composition range the Zr-Be amorphous alloys have two crystallization modes which are dependent on beryllium content in alloys. The temperatures and ac tivation energies for crystallization depend on crystallization-mode a s well as beryllium content. These amorphous alloys were put into prac tical use in joining bearing pads on zircaloy cladding sheath. Using Z r-Be amorphous alloys as filler metals, the reduction in thickness of cladding sheath wall are prevented. Especially, in the case of using Z r0.65Be0.35 and Zr0.7Be0.3 amorphous alloys, smooth interface and sphe rical primary alpha-Zr particles appear in the brazed layer, which is desirable microstructure in the view of the corrosion-resistance. (C) 199S Elsevier Science B.V.