Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Corrosion of Zircaloy-4 joints brazed with Zr-Cu-X filler alloys was investigated. </LI> <LI> Alloyed Al deteriorated the overall nobility of joints by microgalvanic reaction. </LI> <LI> Compositional gradient of Al in joints was the driving force for galvanic corrosion. </LI> <LI> Cu and Fe did not influence the electrochemical stability of joints. </LI> <LI> Zr-Cu-Fe filler alloy yielded excellent high-temperature corrosion resistance. </LI> </UL> </P>