Metallurgist, Argonne National Laboratory, Material Science and Technology Division, Argonne, IL
Pages: 24 Published: Jan 1987
Microstructural evolution in Zircaloy-2 and -4 spent-fuel cladding specimens after three years of irradiation in commercial power reactors has been investigated by transmission and high-voltage electron microscopies. Two kinds of precipitates induced by the fastneutron irradiation in the reactors have been identified, that is, Zr3O and cubic-ZrO2 particles approximately 2 to 10 nm in size. By means of specimen tilting and dark-field stereomicroscopy, the bulk nature of the cubic-ZrO2 particles has been shown. The Zr(Fex,Cr1−x)2 and Zr2(Fex,Ni1−x) intermetallic precipitates normally present in the as-fabricated material virtually dissolved in the spent-fuel cladding specimens after a fast-neutron fluence of ∼4 × 1021 n/cm2 in the power reactors. The observed radiation-induced phase transformations are discussed in relation with the currently available understanding of the alloy characteristics.
Zircaloys, irradiation, precipitates, stereomicroscopy, brittle failure
Paper ID: STP33851S