Electrochemical roles of precipitates on uniform corrosion and hydrogen pickup of zirconium alloys, (I) Roles on corrosion

Substantial roles of precipitates such as Zr-Fe-Cr type intermetallic compo unds on uniform corrosion and hydrogen pickup of zirconium alloys in pure w ater autoclave tests were investigated from an electrochemical point of vie w. This paper describes the roles on corrosion. A corrosion test on precipitate-containing and precipitate-free materials m ade from pure zirconium and a small quantity of iron and chromium. rest pot ential measurements on an intermetallic compound of Zr(FeCr)(2) and zirconi um matrix, and a galvanic coupling test of those were performed. Results sh owed that corrosion behavior of zirconium alloys could be attributed to the electrochemical properties of intermetallic compounds precipitated in each alloy. Namely, the cathodic and anodic polarization characteristics were a ssociated with anodic protection provided by the precipitates on the alloys and the precipitates degradation in the oxide films, respectively. The mec hanism was confirmed through a corrosion lest of Zr-X(X=0.2Fe. 0.2Cr, 0.1Fe -0.1Cr) alloys and electrochemical measurements of ZrFe2, ZrCr2, and Zr(FeC r)(2) intermetallic compounds.