THE SOLID SOLUBILITY OF FE IN ALPHA-ZR - A SECONDARY-ION MASS-SPECTROMETRY STUDY

Secondary ion mass spectrometry techniques have been used to determine the terminal solid solubility (TSS) of Fe in alpha-Zr. Single crystal s of nominally pure and Fe-doped alpha-Zr were annealed in the tempera ture range 770-1100 K to promote equilibration of Fe between surface Z r3Fe precipitates, or beta-Zr(Fe), and alpha-Zr. The results are fair in overall agreement with a recent investigation, based on thermoelect ric power measurements, but they differ in detail. In particular this work indicates two regions of temperature dependence: above 930 K the TSS (ppma) is given by C(Fe) = 1.56 X 10(10) exp(-1.70 +/- 0.05 eV/kT) , at lower temperatures a weaker temperature dependence is associated with extrinsic effects. In addition, the eutectoid temperature is show n to lie between 1063 and 1068 K.