EFFECTS OF PHOSPHORUS ON DEFECT BEHAVIOR, SOLUTE SEGREGATION AND VOID SWELLING IN ELECTRON-IRRADIATED FE-CR-NI ALLOYS

Interstitial loop formation and void swelling under electron irradiation have been observed with a HVEM in pure Fe-15Cr-(13 to 28)Ni and Fe-16Cr-17Ni-(0.024 to 0.1)P alloys at temperatures between 293 and 873 K. After irradiations, microchemical changes at the void surfaces and matrices were analyzed by EDS. At temperatures below 573 K, where the effect of long range migration of vacancies is negligibly small, the interstitial loop density in Fe-Cr-Ni-P alloys was considerably higher than that in pure Fe-Cr-Ni ternaries. At temperatures above 573 K void swelling or vacancy loop formation is prominent and shifted upward by 100 K. Moreover, solute (Ni) segregation to the void surface and matrix were suppressed by phosphorus addition. Such phenomena are thought to be the result of vacancy-phosphorus interaction.