Thermodynamic modelling of the Co-Y system

The Co-Y system was critically assessed by means of the CALPHAD technique. The solution phases (liquid, body-centred cubic, face-centred cubic and hexagonal close-packed) were modelled with the Redlich-Kister equation. The intermetallic compounds Co17Y2 and Co5Y, which have a homogeneity range, were treated as one phase with the formula (Co2,Y)(Co2,Y)2Co15, based on their crystal structures, by a three-sublattice model with Co2 and Y on the first and second sublattices and Co on the third one, respectively. The others Co7Y2, Co3Y, Co2Y, Co3Y2, Co7Y6, CoY, Co3Y4, Co5Y8 and CoY3 were treated as stoichiometric compounds. A set of self-consistent thermodynamic parameters of the Co-Y system was obtained