Phase equilibrium relations of the Mg-Zn-Y system in the low-Y side at 400℃were investigated by alloy-equilibrated method,combined with thermal analysis.The results show that there is a liquid phase which could be in...Phase equilibrium relations of the Mg-Zn-Y system in the low-Y side at 400℃were investigated by alloy-equilibrated method,combined with thermal analysis.The results show that there is a liquid phase which could be in equilibrium with an a-Mg solid solution and an icosahedral quasicrystal I phase in the low-Y side of the Mg-Zn-Y system at 400℃.The liquid phase region originates from the binary Mg-Zn system and extends to 0.4 at%Y in the Mg-Zn-Y system.Besides,the hexagonal structure H phase,fee W phase and LPSO phase(X phase)are in equilibrium with a-Mg.With Y/Zn(atomic ratio,the same as follows)increasing,there exist four three-phase regions consisting of I+liquid+α-Mg,I+H+α-Mg,H+W+α-Mg and W+X+α-Mg,respectively,in the low-Y side of the isothermal section at 400℃.The twophase region a-Mg+I phase exists between I+H+aMg and I+liquid+a-Mg.In this two-phase region,the Y/Zn ratio is in the range of 0.14-0.17;and a three-phase region of a-Mg+I phase+H phase appears when Y/Zn ratio comes up to 0.17-0.27.Not I but W phase is in equilibrium with a-Mg,when Y/Zn ratio>0.27.The system is in liquid-state phase equilibrium,when Y/Zn ratio<0.14.展开更多
The Mg-Al-Zn-Y-Ce system is one of the key systems for designing high-strength Mg alloys. The purpose of the present article is to develop a thermodynamic database for the Mg-Al-Zn-Y-Ce multicomponent system to design...The Mg-Al-Zn-Y-Ce system is one of the key systems for designing high-strength Mg alloys. The purpose of the present article is to develop a thermodynamic database for the Mg-Al-Zn-Y-Ce multicomponent system to design Mg alloys using the calculation of phase diagrams （CALPHAD） method, where the Gibbs energies of solution phases such as liquid, fcc, bcc, and hcp phases were described by the subregular solution model, whereas those of all the compounds were described by the sublattice model. The thermodynamic parameters describing Gibbs energies of the different phases in this database were evaluated by fitting the experimental data for phase equilibria and thermodynamic properties. On the basis of this database, a lot of information concerning stable and metastable phase equilibria of isothermal and vertical sections, molar fractions of constituent phases, the liquidus projection, etc., can be predicted. This database is expected to play an important role in the design of Mg alloys.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51271053 and 5137104)the National Key Research and Development Program of China(No.2016YFB0701202).
文摘Phase equilibrium relations of the Mg-Zn-Y system in the low-Y side at 400℃were investigated by alloy-equilibrated method,combined with thermal analysis.The results show that there is a liquid phase which could be in equilibrium with an a-Mg solid solution and an icosahedral quasicrystal I phase in the low-Y side of the Mg-Zn-Y system at 400℃.The liquid phase region originates from the binary Mg-Zn system and extends to 0.4 at%Y in the Mg-Zn-Y system.Besides,the hexagonal structure H phase,fee W phase and LPSO phase(X phase)are in equilibrium with a-Mg.With Y/Zn(atomic ratio,the same as follows)increasing,there exist four three-phase regions consisting of I+liquid+α-Mg,I+H+α-Mg,H+W+α-Mg and W+X+α-Mg,respectively,in the low-Y side of the isothermal section at 400℃.The twophase region a-Mg+I phase exists between I+H+aMg and I+liquid+a-Mg.In this two-phase region,the Y/Zn ratio is in the range of 0.14-0.17;and a three-phase region of a-Mg+I phase+H phase appears when Y/Zn ratio comes up to 0.17-0.27.Not I but W phase is in equilibrium with a-Mg,when Y/Zn ratio>0.27.The system is in liquid-state phase equilibrium,when Y/Zn ratio<0.14.
基金This study was financially supported by the National Natural Science Foundation of China and Chongqing Science and Technology Commission.
文摘The Mg-Al-Zn-Y-Ce system is one of the key systems for designing high-strength Mg alloys. The purpose of the present article is to develop a thermodynamic database for the Mg-Al-Zn-Y-Ce multicomponent system to design Mg alloys using the calculation of phase diagrams （CALPHAD） method, where the Gibbs energies of solution phases such as liquid, fcc, bcc, and hcp phases were described by the subregular solution model, whereas those of all the compounds were described by the sublattice model. The thermodynamic parameters describing Gibbs energies of the different phases in this database were evaluated by fitting the experimental data for phase equilibria and thermodynamic properties. On the basis of this database, a lot of information concerning stable and metastable phase equilibria of isothermal and vertical sections, molar fractions of constituent phases, the liquidus projection, etc., can be predicted. This database is expected to play an important role in the design of Mg alloys.
