Atom probe characterisation of segregation driven Cu and Mn–Ni–Si co-precipitation in neutron irradiated T91 tempered-martensitic steel

Nanocluster evolution and mechanical properties of ion irradiated T91 ferritic-martensitic steel

“…Regarding nucleation sites for MNSP, it should be noted that Cu impurities were detected in all APT datasets, however, no evidence of clustering was observed. The role of Cu clustering under neutron and ion irradiation within Fe-Cr and RPV steels has been observed and has been shown to play a significant role in the nucleation of MNSPs [33,34,42,46,66].…”

“…Thus, the overlap at 29 Da could potentially be incorporated within MNSPs. In this work, all cluster compositions include the 29 Da peak and are labelled as 58 Ni 2+ (and not 29 Si 1+ as the isotopic ratios for neighbouring peaks did not match natural levels), and this method has been used in previous studies [33,64,65]. Fe ions are also removed from all cluster calculations based on previous methods [64,65].…”

“…Therefore, it then naturally follows to investigate the clustering dependence on irradiation dose on such a commercially used steel. Refs [3,30] did not include any Mn alloying addition and it is known for T91 steel that Mn clusters with Ni and Si [3][4][5][6][7][8] to form MNSPs [3][4][5][6][7][8]32,33]. In terms of specific issues in commercial Fe-Cr systems requiring greater examination, the role of Mn, Ni, Si and P in T91 steel has not been studied at single specific temperature across a range of ion irradiation doses to understand the role of each solute and impurity atoms have on the evolution of the microstructure.…”

“…Gómez-Ferrer et al [30] observed Ni clustering in their APT data after heavy ion irradiation to 0.5 dpa at 300 o C, but did not see any clustering below this dose value. Most Fe-Cr-based commercial alloys, such as T91, have been known to form MNSP under both neutron [3,4,8,28,[33][34][35][36][37][38] and proton irradiation [3,26,27,29,39,40]. Furthermore, [33] have shown that parallels can be drawn between the understanding of precipitation in reactor pressure vessel (RPV) steels (low alloy ferriticbainitic steels [41][42][43][44][45][46][47][48][49]) and Fe-Cr based alloys (T91, HT9 etc) [1,2,27,50].…”

“…Most Fe-Cr-based commercial alloys, such as T91, have been known to form MNSP under both neutron [3,4,8,28,[33][34][35][36][37][38] and proton irradiation [3,26,27,29,39,40]. Furthermore, [33] have shown that parallels can be drawn between the understanding of precipitation in reactor pressure vessel (RPV) steels (low alloy ferriticbainitic steels [41][42][43][44][45][46][47][48][49]) and Fe-Cr based alloys (T91, HT9 etc) [1,2,27,50]. The major differences between RPV steels and Fe-Cr steels are that the latter's solute contents (Ni, Si, Mn, etc.)…”