Thermodynamic Stability of Fe-Cr Binary System: The Crucial Role Of Magnetic Contribution As Elucidated By Calorimetric Measurements

摘要

The influence of magnetic interactions on high temperature thermodynamic stability of Fe-Cr binary system has been analysed in the light of accurate isothermal calorimetry measurements (400-1473 K) on Fe-20wt.%Cr alloy. The onset of two successive principal transformations namely, (i) a'(Fe-rich bcc)+a"(Cr rich bcc)→a(HT bcc) at 702+10 K; and (ii) a_(ferro)→a_(fpara) at 925 ±10 K, with their associated enthalpy effects (△~oH_(mag) = 2 kJ mol~(-1); C_p~(mag) = 20 J mol~(-1) K~(-1)) have been clearly delineated by the measured enthalpy variation with temperature. A precise quantification of magnetic contribution to high temperature thermodynamic stability has been attempted using physically based modelling approach.