N. Shigenaka et al., RADIATION-INDUCED SEGREGATION AT GRAIN-BOUNDARY IN AN AUSTENITIC STAINLESS-STEEL UNDER ION IRRADIATION, Journal of Nuclear Science and Technology, 33(6), 1996, pp. 474-478
Chromium depletion near grain boundaries of austenitic stainless steel
during irradiation was investigated. Specimens were kept at 1,473 K f
or 30 min, and were quenched into the water. Irradiations were done us
ing 400 keV He+ ions at 573, 673 and 773 K up to 10 dpa with a dose ra
te of 2.4x10(-4) dpa/s. After irradiation, the Cr concentration profil
e near the grain boundary was measured using an analytical electron mi
croscope with a 1 nm beam diameter. At 573 K, Cr depletion is small, a
nd its concentration at the grain boundary decreases to 15.5 mass% at
3dpa from the initial concentration of 18.5 mass%. At 673 and 773 K, C
r concentration at the grain boundary rapidly decreases between 0 and
0.2 dpa, and then gradually approaches a constant value, 7.0 mass% at
673 K and 5.0 mass% at 773 K. Two stages are found in radiation induce
d segregation (RIS) behavior, one stage in which Cr depletion and Ni e
nrichment balance and another in which Fe depletion and Ni enrichment
balance. These experimental results were compared with the calculation
s based on the vacancy-induced inverse Kirkendall effect. Predicted Cr
segregation at 673 and 773 K above 3 dpa agrees with the experimental
results. But Cr depletions at low doses which were obtained in the ex
periments are much faster than calculated. At 573 K in the experiments
, depletion is smaller than calculated up to 10 dpa.