Transmission electron microscopy studies on intermetallics in some zirconium alloys

Intermetallics in zirconium alloys, including zircaloy-2, Zr/1%Nb (scanuk 1) and Zr/0.5% Nb/0.5% Cr (scanuk 4), have been examined using transmission electron microscopy. On the basis of diffraction studies, the composition and structure of several precipitates have been determined. In recrystallized zircaloy-2 bct precipitates with the lattice parameters of a₀=b₀=6.5Å and c₀=5,5Å, were found. These precipitates were presumably a Zr/Ni/Fe compound. In recrystallized Zr/1% Nb alloy, bcc β-niobium precipitates with a lattice parameter of a₀=3.45Å  were observed. In recrystallized Zr/0.5%Nb/0.5% Cr alloy the precipitates were fcc ZrCr2, with a lattice parameter of a₀=7.4Å. The structure of the graincorner regions in (α + β)-treated Zr/1%Nb alloy, as well as the hydrides both in recrystallized Zr/1%Nb alloy and zircaloy-2, have also been discussed.