A TEM investigations were conducted on the heat treated zircaIoy-2 having the composition of Zr containing 1.6 % Sn, 0.2 % Fe, 0.1 % Cr and 0.05 % Ni (% wt) in order to study the characteristics of intermetallic particles related to the microstructural basis on the corosion effect. Forged zircaloy-2 was annealed in the p-phase at 1050°C for various durations, followed by water quenching. The p-quenched specimens were then annealed isothermally in the a-phase region at 650 and 750°C, followed by water quenching. The size distribution of intermetallic particles showed a tendency as the coarser become the precipitates, the lower becam their number. By increasing the annealing temperature, the growth of precipitates became more profound than by increasing the annealing time. The kind of precipitates formed in this zircaloy-2 were of the Zr(Cr,Feh and Zr2(Fe,Cr,Ni) types. These kinds of precipitates and the ratios of Fe/Cr were independent of size and shape of precipitates and annealing time and temperature in the a-phase region. Harini Sosiati Sudarminto, Noriyuki Kuwano, Kensuke Oki,
