The oxidation of γ-Zr(Fe,Cr)2 intermetallic particles during the thermal exposition of
Zircaloy-4 at 470°C in oxygen was investigated with PhotoElectroChemical techniques (PEC). Via
the measurement of bandgap, haematite Fe2O3 (2.2 eV), rhomboedric solid solution (FexCr1-x)2O3
(2.6 eV) and chromia Cr2O3 (3.0 eV) phases were identified as components of oxidised particles.
Evolution of size, lateral distribution and density of these particles was studied in function of
zirconia scale thickness. During the first stage of oxidation, the density of oxidised particles
increased with thickness but decreased during a second stage, highlighting in an innovative way the
phenomenon of haematite and chromia dissolution in the zirconia matrix. It is concluded that PEC
techniques represent a sensitive and powerful way to locally analyse the various semiconductor
phases in an oxide scale at the micron scale.