Anomalous Temperature-Dependent Behavior of Physical Properties of CrFeNi, CoCrNi, and CoCrFeNi Medium- and High-Entropy Alloys

Abstract

The linear thermal expansion coefficient, heat capacity, electrical resistivity, and its temperature coefficient d(In R)/dT of the medium-entropy CrFeNi and CoCrNi alloys and CoCrFeNi high-entropy alloy revealed an anomalous behavior in the temperature range of 700 – 900 K. The behavior is not only different between the first and second heating, but also between the first heating and the first cooling. However, a minimum in α and C_p and a maximum in d(In R)/dT are only observed in the first heating. Magnetic moment measurements as a function of temperature proved that the observed anomalies are not associated with the Curie temperature. Consideration of the structural and microstructural features also discards recrystallization as a probable cause. The anomalies are believed to be caused by chemical short-range order transition known as the K-state effect.

Keywords: High-entropy alloy, Dilatometry, Differential scanning calorimetry, Electrical resistivity, Short-range ordering