AbstractAn adiabatic calorimeter was used to measure the molar heat capacities and heats of transformation of iron alloys containing up to 14 at.-% Cr and 15 at.-% Co over the temperature range 700–1500 K. A Sucksmith magnetic balance was used to measure the magnetic properties of these alloys and of Fe–Co and Fe–Cr alloys previously investigated calorimetrically. In all but one of the ternary alloys theα→γtransformation occurred at a temperature below the Curie temperature (Tc), but the heats of transformation, corrected to the transformation temperature of pure iron (1184 K), correlated well with the difference between the extrapolated Curie temperature and 1184 K, as had been observed previously for alloys with clearly defined values of Tc. The fact that all observations fell on the same curve supported the proposal that a significant amount of magnetic order remains after theα→γtransformation for most iron alloys.MST/198