Anomalous concentration dependence of residual electrical resistivity in Fe-Cr alloys

Abstract

Experimental data on the residual electrical resistivity in concentrated Fe-Cr alloys point to strong deviation from Nordheim-like behavior: resistivity stays nearly constant over 10-60 at. % Cr concentration range. These data are compared to the results of calculations conducted in a two-band coherent potential approach for a ferromagnetic phase. The anomalous behavior of residual resistivity turns out to be a result of two opposite tendencies: increasing with chromium concentration scattering probability is compensated by concurrent reduction in density of states at the Fermi level.

Electronic transport in ferromagnetic alloys and the Slater-Pauling curve

“…This is in variance to an earlier theoretical study 8 which finds the starting point of the plateau only at Ϸ20% Cr. …”

“…The measurements show that the resistivity increases as small amounts of Cr are added to Fe until a plateau is reached ranging from x =10% to 20%. 8 This behavior differs markedly from the Nordheim parabolic concentration dependence. An analysis of the data is hindered by a complexity of short-range order in Fe 1−x Cr x .…”

“…In Ref. 8 it is argued that this is a consequence of the limitations of the CPA for alloys with a dominant concentration of one constituent. However, it should be pointed out that our NL-CPA results confirm the single-site CPA data.…”

“…[3][4][5][6] In this paper we follow the implications of this for the residual resistivities of ferromagnetic alloys. In particular, using the latest ab initio techniques for describing disordered systems, we demonstrate how the measured apparently anomalous resistivities of iron-rich Fe 1−x Cr x alloys 7,8 are directly attributable to their average minorityspin electron number being fixed and consequently their location on the dM dN v = + 1 section of the Slater-Pauling plot. We postulate that other alloys in this category should also show the same behavior, and we strengthen this conjecture by the findings from another detailed ab initio study of Fe 1−x V x alloys.…”

Microstructural stability of Fe–Cr–Al alloys at 450–550 °C

“…The α-α' phase separation results in a modulation of the material's composition [46]. This means that pathways, which are better electrical conductors, are formed due to change in local composition, thus the electrical resistance is reduced while the material is aged in the critical temperature interval [47]. As for the hardness test, the reference alloy showed clear signs of phase separation, indicated by a decrease in the electrical resistance during short-term aging.…”