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DSC investigation of binary iron-nickel alloys
Andrzej J. Panas, and Dagmara Panas
Differential scanning calorimetry (DSC) measurements on a range of binary iron-nickel (Fe-Ni) alloys, including invar, are reported. The study was conducted to verify and supplement existing knowledge of thermophysical properties of Fe-Ni alloys with a focus on magnetic phase transition. There were 11 investigated samples altogether, spanning nickel contents from 10 to 72 wt%. The measurements were performed within a range from 253 K to 870 K applying power compensation DSC apparatus. A specially developed thermal program with linear steps interrupted by isotherms was used enabling investigations on both heating and cooling. Specific heat at constant pressure as a function of temperature was obtained using the three-curve method. The collected DSC data were processed using B-spline approximation procedures. The obtained thermal characteristics are reported altogether with the identified characteristic temperatures of the observed phase transitions. Results of supplementary density measurements are provided as well. The study revealed inconsistency in the literature data concerning Curie temperature.
Keywords: Differential scanning calorimetry, specific heat, phase transitions, binary alloys, invar, B-spline approximation.