An improved thermodynamic modeling of the Fe-Cr system down to zero kelvin coupled with key experiments
Artikel i vetenskaplig tidskrift, 2011

A thermodynamic modeling of the Fe-Cr system down to 0 K is performed on the basis of our recent comprehensive review of this binary system [W. Xiong, M. Selleby, Q. Chen, J. Odqvist, Y. Du, Evaluation of phase equilibria and thermochemical properties in the Fe-Cr system, Crit. Rev. Solid State Mater. Sci. 35 (2010) 125-152]. The model predicts a sign change for the magnetic ordering energy of mixing rather than the enthalpy of mixing in the bcc phase at 0 K. Designed key experiments are performed not only to check the validity of the present modeling but also to assist in understanding the mechanism for spinodal decomposition of the Fe-Cr alloy. Heat capacities and Curie temperatures of several Fe-rich alloys are determined between 320 and 1093 K by employing differential scanning calorimetry. The measured heat capacities are found to be in remarkable agreement with the prediction based on the present modeling. Microstructural patterns and frequency distribution diagrams of Cr are studied in alloys containing 26.65, 31.95, and 37.76 at.% Cr by using atom probe tomography. The observed phase separation results correspond well with our model-predicted boundary for the spinodal decomposition. Interestingly, a horn on the Cr-rich spinodal boundary is predicted below 200 K for the first time. This work demonstrates a way to bridge the ab initio calculations and CALPHAD approach.

Heat capacity

liquid

iron

Phase separation

ni-cr

Stainless steels

Magnetic

Atom probe

miscibility gap

alloys

chromium

mossbauer

diagram

sigma-phase

Ab initio calculations

high-temperature calorimeter

Författare

W. Xiong

Kungliga Tekniska Högskolan (KTH)

P. Hedstrom

Kungliga Tekniska Högskolan (KTH)

M. Selleby

Kungliga Tekniska Högskolan (KTH)

J. Odqvist

Kungliga Tekniska Högskolan (KTH)

Mattias Thuvander

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Q. Chen

Thermo-Calc Software AB

Calphad: Computer Coupling of Phase Diagrams and Thermochemistry

0364-5916 (ISSN)

Vol. 35 355-366

Ämneskategorier

Fysik

DOI

10.1016/j.calphad.2011.05.002