Change of Cr atoms distribution in Fe85Cr15 alloy caused by 250keV He+ ion irradiation to different doses

Abstract

Redistribution of Cr atoms in a Fe 85 Cr 15 alloy caused by its irradiation with 250 keV He + ions to different doses, D=810 16 , 1610 16 and 4810 16 ions/cm 2 was investigated by means of conversion electrons Mӧssbauer spectroscopy. The redistribution was expressed in terms of the Warren-Cowley short-range order parameters  1 ,  2 and  12 pertaining to the first (1NN), second (2NN) and both i.e. 1NN+2NN shells, respectively. Clear evidence was found, both for non-irradiated and irradiated samples that the actual distribution of Cr atoms is characteristic of the shell, and for a given shell it depends on the irradiation dose. In particular,  1 is positive, hence indicates an under population of Cr atoms in 1NN with respect to the random case,  2 is negative, giving evidence thereby that 2NN is overpopulated by Cr atoms, and  12 is weakly positive. Under the applied irradiation the number of Cr atoms in both neighbor shells decreased signifying thereby a clustering of Cr atoms. The underlying decrease of Cr concentration within the 1NN-2NN volume around the probe Fe atoms was estimated at 1.5 at% ranging between 2.1 for the lowest and 0.8 at% for the highest dose.

Effect of 0.25 and 2.0 MeV He-Ion Irradiation on Short-Range Ordering in Model (EFDA) Fe-Cr Alloys

“…Very good fits (in terms of a  2 -test) were obtained with the spectral parameters displayed in Table 1. Their values are in close agreement with the corresponding values reported previously [20][21][22][23][24][25][26][27][28].…”

“…It is well known that clustering of Cr atoms in Fe-Cr alloys and in Fe-Cr based steels results in an enhanced embrittlement, hence the redistribution cannot be neglected. 15 The observed irradiation-induced changes in the distribution of Cr atoms within the 1NN-2NN volume around the probe Fe atoms can be also expressed in terms of underlying changes in the local concentration of Cr, xk, defined as follows [26]:…”

“…The observed irradiation-induced changes in the distribution of Cr atoms within the 1NN-2NN volume around the probe Fe atoms can be also expressed in terms of underlying changes in the local concentration of Cr, xk, defined as follows [26]:…”

“…MS has already proved to be a relevant method for the quantitative investigation of Fe-Cr alloys. Notably issues connected to determination of a distribution of Cr atoms in Fe matrix e. g. [21][22][23][24][25][26][27], the solubility limit of chromium [28,29] and the kinetics of ' precipitation [29] can be successfully studied with high precision using MS.…”

Dynamics of magnetism in Fe-Cr alloys with Cr clustering

“…The kinetics of Cr clustering in Fe-Cr alloys has been studied extensively through experimental 26,[30][31][32][33][34] and theoretical approaches 27,34,35 . However, the effect of Cr precipitation on the magnetic properties of Fe-Cr alloys has largely been ignored from quantitative analysis.…”