PSEUDOBINARY ZIRCALOY-OXYGEN PHASE-DIAGRAM

The zirconium-rich portion of the pseudobinary zircaloy-4/oxygen phase diagram was investigated by resistometric measurements and by metallographic analysis of equilibrated and quenched specimens. Accurate results for the phaseboundary locations were obtained from metallographic analysis of specimens in which oxidation and homogenization were limited to the α-phase region, and the specimens were rapidly quenched from equilibration temperatures in the β- and (αa + (β)-phase regions. The a- and (3-phase boundaries can be represented by the realtions In Cα = -2.28 + 0.535 In (T - 1083) and In Cβ = 5.02 - 8 220/T (for T > 1280 K or Cβ > 0.2), where Cα and Cβ are the oxygen concentrations in weight percent and T is temperature in K. © 1979.