Abstract: A series of zirconium alloys with copper and manganese additions in Zircaloy-4 were prepared using a vacuum non-consumable arc melting method. TEM observationwas carried out to characterize precipitates in alloys. The crystal structure was determined by a selected area electron diffraction (SAD) pattern, and the composition of precipitates was analyzed with energy dispersion spectroscopy (EDS). In the copper-added Zircaloy-4 specimens, three main precipitates were detected: (1) Zr(Fe,Cr)₂ precipitates, (2) Zr(Fe,Cr,Cu)₂ precipitates, and (3) Zr₂Cuprecipitates with a bit of Fe or without Fe. In the manganese-added Zircaloy-4 specimens, only one kind of Zr(Fe,Cr,Mn)₂ precipitate was observed. Mn content in the precipitates increased as the increase of Mn content from 0.07% to 0.35% in the alloy.

Key words: alloying element, microstructure, precipitates
, zirconium alloys