Regular Article

Thermodynamic assessment of Hafnium Iridium binary system

¹ Centre Régional des Métiers de l’Éducation et de la formation, Inezgane, Maroc
² Laboratoire Génie de l’Énergie, Matériaux et Systèmes, ENSA, Université Ibnou Zohr, BP 1136 Agadir, Maroc
³ Laboratoire de Physicochimie de l’État Solide, ICMMO, Université Paris-Sud, 91405 Orsay Cedex, France

^* e-mail: idbenalimohamed@yahoo.fr

Received: 4 March 2017
Accepted: 2 January 2018

Abstract

The Hf–Ir system has been thermodynamically modeled by the CALPHAD approach. Hf₂Ir, αHfIr, βHfIr, γHfIr (high temperature phase) and HfIr₃ which have a homogeneity range, were treated as the formula (Hf,Ir)_x:(Ir,Hf)_1−x by a two-sublattice model with a mutual substitution of Hf and Ir in both sublattices.Hf₅Ir₃ has been treated as a stoichiometric compound while a solution model has been used for the description of the FCC (Ir) solid solution. Additionally, two different models describing the excess Gibbs energy for the liquid and for the solid solutions (BCC, FCC and HCP) were used and their predictions are compared. The calculations based on the thermodynamic modeling are in good agreement with the phase diagram data and experimental thermodynamic values available in the literature.