APT characterization of high nickel RPV steels

APT characterization of irradiated high nickel RPV steels

“…The compositional variation of this weld as a function of distance through the weld [0.21-0.32 wt% Cu (0.18-0.28 at.% Cu)] has been reported previously [24]. The nickel content of this weld was 0.58-0.63 wt% Ni (0.55-0.59 at.% Ni).…”

“…Atom probe tomography has been used previously to characterize several neutron irradiated RPV steels and model alloys including some characterizations of the weld material from the Palisades and Midland reactors [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The change in the copper solubility in the matrix of a submerged arc beltline weld (designated a Babcock and Wilcock WF-70 weld) from the Midland reactor after exposure to a fluence of 1.1 · 10 23 n m À2 (E > 1 MeV), and also thermal annealing experiments have been reported previously [24]. Atom probe analysis revealed a substantial depletion in the copper content of the matrix after the stress relief treatment to 0.119 ± 0.007 at.% Cu with a further depletion to 0.058 ± 0.008 at.% Cu together with the precipitation of some ultrafine copper-enriched precipitates after neutron irradiation.…”

Embrittlement of RPV steels: An atom probe tomography perspective

“…An example of these nickel-, manganese-and silicon-enriched clusters in a weld with a Russian VVER 1000 type reactor composition that was neutron irradiated in the Ford test reactor to a total fluence of 1.4 · 10 23 n m À2 (>1 MeV) [2.4 · 10 23 n m À2 (>0.5 MeV)] at a temperature of 288°C is shown in Fig. 9 [25]. These $1-2-nm-diameter clusters are similar in size to or slightly smaller than the copper-enriched precipitates.…”

Three Dimensional Atom Probe Study of Ni-Base Alloy/Low Alloy Steel Dissimilar Metal Weld Interfaces

“…There are similar precedents that some precipitates were observed by 3D APT. Miller et al [23][24][25][26][27][28][29][30][31][32][33][34][35] observed copper-, nickel-, manganese-and silicon-enriched precipitates in reactor pressure vessel weld steel and base steel by using 3D APT. They applied the technology of 3D APT to show that the precipitates coarsened during neutron irradiation and post irradiation heat treatment.…”