Mechanical property change in neutron irradiated Fe-Cr and Fe-Mn alloys, and their defect structures

Multiscale modelling of radiation damage and phase transformations: The challenge of FeCr alloys

“…In addition, the validity of the data suggesting the deep radiation-embrittlement minimum at 9%Cr presented in [59] has been recently questioned [153], on the basis of the proven inadequacy of Charpy tests to predict the shift of the ductile-brittle transition temperature under irradiation in ferritic/martensitic steels. According to this argument, Charpy tests would understimate the actual shift when martensite is in the microstructure; as a consequence, the deep minimum should be interpreted in the best case as a shallow minimum [153], thereby providing a better correlation with hardening data, that suggest a plateau instead [48,52,60,61]. If, therefore, we stick to radiation-hardening data, based on the current qualitative understanding of radiation effects in FeCr presented and discussed in the present paper, as well as on experimental indications from the literature on the Cr dependence of the proportion of ½\111[ and \100[ dislocation population under irradiation [54,55,154], a simplified, mechanistic approach can be proposed, whereby the radiation-hardening, Dr y , would be the result of the composition of different contributions: …”

“…As mentioned in the introduction, the scarce data concerning radiationhardening in FeCr alloys versus Cr content are not fully consistent with each other and with radiation-embrittlement data. In particular, while three sets of data [48,52,60,61] seem to be consistent in showing higher radiation-hardening as soon as Cr is added to Fe, with a kind of plateau, followed by increased hardening above 9%Cr, one early set of data [62] suggests linear increase. In addition, embrittlement data suggest a deep minimum at 9%Cr [59], which is not found (so far) in hardening data.…”

“…Searching for the reason for this initially 'mysterious' effect [67] led to the identification of the existence of the miscibility gap between Fe-rich (a) and Cr-rich (a 0 ) bcc phases [68,69], that characterises the currently accepted FeCr phase diagram. Yet, it is not equally apparent how to rationalize the overall higher radiation-induced hardening in FeCr compared to pure Fe, not matched by the visible defect density [48,60,61], and even less to understand the reasons of the DDBTT (local?) minimum at $9%Cr, i.e.…”

“…For this reason in recent years significant effort has been put, particularly in Europe and in the USA, in atomic-level studies, with a view to developing multiscale models of the response to irradiation of FeCr alloys , the reference model system to understand the behaviour of high-Cr steels [2,6,[48][49][50][51][52][53][54]. These models have the ambition of deducing the macroscopic response of the material to given conditions starting from a detailed knowledge of the fundamental interactions between atoms.…”

The effect of copper and manganese on magnetic minor hysteresis loops in neutron irradiated Fe model alloys

“…For both VA and VB alloys, Dr y is about 50 MPa and is relatively small compared with that for VH and VD alloys. The increase of the yield strength for VA and VB alloys is mainly attributed to the formation of dislocation loops, though for VB alloy fine scale manganese-vacancy clusters in subnanometer size are considered to give additional effects [5,31].…”