Magnetic Phase Transition of Chromium-Rich Chromium-Iron Alloys

Specific heats of Cr-rich Cr–Fe alloys were measured with an AC-calorimeter. In the range of Fe content less than 1.6 at.%, anomalies due to the transition from paramagnetic to incommensurate spin density wave state (I) are observed together with the stepwise changes for Cr and 0.4 at.% Fe sample. The ordering sequence of paramagnetic-I-commensurate spin density wave state (C) is recognized only on 2.0 at.% Fe sample. The phase boundary of the I–C transition is in a narrow range of Fe content on the low concentration side of the triple point. In the range of Fe content higher than 3.0 at.%, only the P–C transition is observed. The first order P–C transition changes to the second order at a critical point located somewhere around 4.9 at.% Fe.