Phase equilibria in Ti-rich portion and thermodynamic re-optimization of Co-Ti system
作者机构：Faculty of Materials Metallurgy and ChemistryJiangxi University of Science and TechnologyGanzhou 341000JiangxiChina Jiangxi Advanced Copper Industry Research InstituteYingtan 335000JiangxiChina
出 版 物：《Journal of Iron and Steel Research(International)》 (钢铁研究学报（英文版）)
年 卷 期：2022年第29卷第6期
页 面：914-924页
核心收录：
学科分类：08[工学] 0806[工学-冶金工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学]
主 题：Co-based superalloy Co-Ti system Phase equilibrium CALPHAD method Order–disorder transformation
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.
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