摘要
The experimental and thermodynamic studies of the Co-Ti system are an important part of the project to build a thermodynamic database for multicomponent Co-Ti-based alloys.Several key alloys were prepared and then examined for microstructural,compositional and thermal analyses to determine the Ti-rich phase equilibria.According to the available experimental information,the Co-Ti system was thermodynamically re-optimized on the basis of CALPHAD method.Four disordered solutions,liquid,fcc-A1(α-Co),bcc-A2(β-Ti)and hcp-A3(ε-Co andα-Ti)were modeled as substitutional ones.CoTi_(2)with limited solubility was treated as a stoichiometric compound,whileγ-Co_(2)Ti andβ-Co_(2)Ti with certain solubility were described in the form of(Co,Ti)2(Co,Ti)1 using a two-sublattice model.A single Gibbs energy function was employed to model two order–disorder transformations from fcc-A1 to fcc-L12(Co3Ti)and from bcc-A2 to bcc-B2(CoTi).A group of self-consistent thermodynamic parameters of the Co-Ti system were obtained.With these thermodynamic parameters,the experimental data can be described more reasonably and satisfactorily.
基金
This work was supported by Scientific Research Starting Foundation for Advanced Talents of Jiangxi University of Science and Technology(Grant No.205200100063)and Open Foundation of Jiangxi Advanced Copper Industry Research Institute.
