On the basis of the experimental data of phase equilibria and thermochemical properties available from literatures, a critical assessment for the Ni?Yb binary system was carried out using the CALPHAD (calculation of p...On the basis of the experimental data of phase equilibria and thermochemical properties available from literatures, a critical assessment for the Ni?Yb binary system was carried out using the CALPHAD (calculation of phase diagrams) method. The liquid phase is modeled as the associate model with the constituent species Ni, Yb and YbNi3, owing to the sharp change of the enthalpy of mixing of liquid phase at the composition of around 25% Yb (mole fraction). The terminal solid solutions FCC_A1 (Ni/Yb) and BCC_A2 (Yb) are described by the substitutional solution model with the Redlich?Kister polynomial. The intermetallic compounds, Yb2Ni17, YbNi5, YbNi3, YbNi2, α-YbNi and β-YbNi, are treated as strict stoichiometric compounds, since there are no noticeable homogeneity ranges reported for these compounds. A set of self-consistent thermodynamic parameters for the Ni?Yb binary system are obtained. According to the presently assessed results, the thermochemical properties and the phase boundary data can be well reproduced.展开更多
As an example of the La-Mg-Y system, the method how to set up the themaodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases （liquid, body-centered cubic...As an example of the La-Mg-Y system, the method how to set up the themaodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases （liquid, body-centered cubic, face-centered cubic, hexagonal close-packed and double hexagonal close-packed） were modeled with the Redlich-Kister equation. The compound energy model has been used to describe the thermodynamic functions of the intermetallic compounds in the La-Mg-Y systems. The compounds Mg2Y, Mg24Y5, Mg12La, Mg17La2, Mg41Las, Mg3La and Mg2La in the La-Mg-Y system were treated as the formulae （Mg,Y）2（La,Mg,Y）, Mg24（La,Mg,Y）4Y, Mg12（La, Y）, Mg17（La,Y）2, Mg41（La,Y）5, Mg3（La,Mg,Y） and Mg2（La, Y）, respectively. A model （La, Mg,Y）0.5（La,Mg,Y）0.5 was applied to describe the compound MgM formed by MgLa and MgY in order to cope with the order-disorder transition between body-centered cubic solution （A2） and MgM with CsCl-type structure （B2） in the La-Mg-Y system. The Gibbs energies of individual phases were optimized in the La-Mg, La-Y and La-Mg-Y systems by CALPHAD technique. The projection of the liquidus surfaces for the La-Mg-Y system was predicted. The Mg-based alloys database including 36 binary and 15 ternary systems formed by Mg, Al, Cu, Ni, Mn, Zn and rare earth elements was set up in SGTE standard.展开更多
The Gibbs energies of liquid phases in the LaI3-MI （M= Na, K, Cs） systems were described by the modified quasi-chemical model. From the measured phase equilibrium data of these binary systems, a set of thermodynamic...The Gibbs energies of liquid phases in the LaI3-MI （M= Na, K, Cs） systems were described by the modified quasi-chemical model. From the measured phase equilibrium data of these binary systems, a set of thermodynamic functions were optimized by using the CAL- PHAD technique. The enthalpy of mixing and the interaction parameter of the liquid phase were predicted from known data for the LaI3-MI systems.展开更多
Based on the available experimental phase equilibrium relations and aging precipitation sequences,the Mg–Gd–Y ternary system has been thermodynamically re-assessed by means of CALPHAD technique.To simulate the exper...Based on the available experimental phase equilibrium relations and aging precipitation sequences,the Mg–Gd–Y ternary system has been thermodynamically re-assessed by means of CALPHAD technique.To simulate the experimentally reported aging precipitation sequence,α(Mg)_(SS)(supersaturated)→GP zones(D019-type,metastable)→β’-Mg_(7)Gd(c-bco,metastable)→β_(1)-Mg_(3)Gd(fcc,metastable)→β-Mg_(5)Gd(fcc,stable)near the Mg–Gd side,andα(Mg)SS(supersaturated)→β’-Mg_(7)Y(c-bco,metastable)→β-Mg_(24)Y_(5)(bcc,stable)near the Mg–Y side,the effective nucleation driving forces obtained by deducting the nucleation resistances from the thermodynamic driving forces are calculated and analyzed.Two metastable components,GP zones(D019-type)andβ’(c-bco)ordered fromα(Mg)_(SS),do not exist in the stable equilibrium phase diagram but appear in the annealing process of typical alloys.The Redlich–Kister equations are adopted to describe three solution phases,Liquid,HCP_A3 and BCC_A2.The intermediate compounds Mg_(2)Y,Mg_(24)Y_(5),Mg_(2)Gd,Mg_(3)Gd and Mg_(5)Gd are expressed by the formulas of(Mg,Y)_(2/3)(Gd,Mg,Y)_(1/3),Mg_(24/29)(Gd,Mg,Y)_(4/29)Y1/29,(Gd,Mg)_(2/3)(Gd,Mg,Y)_(1/3),(Gd,Mg)_(3/4)(Gd,Mg,Y)_(1/4)and Mg_(5/6)(Gd,Mg,Y)_(1/6),respectively.In particular,the two-sublattice models(Gd,Mg,Y)_(1/2)(Gd,Mg,Y)_(1/2),(Gd,Mg,Y)_(3/4)(Gd,Mg,Y)_(1/4)and(Gd,Mg,Y)_(7/8)(Gd,Mg,Y)_(1/8)have been respectively used to describe the stable Mg(Gd,Y)(BCC_B2)alloy compound as well as the metastable GP zones(D019-type)andβ’(c-bco)phase,in order to cope with the order-disorder transitions.A set of self-consistent thermodynamic parameters has been obtained to ensure the thermodynamic calculations well consistent with the reported experimental data,containing not only the stable equilibrium phase diagram but also the aging precipitation sequence.展开更多
The thermodynamic optimization of the Sn-Y and Mg-Sn-Y systems was critically carried out by means of the CALPHAD（CALculation of PHAse Diagram） technique. In the Sn-Y system, the solution phases（liquid, bcc, bct an...The thermodynamic optimization of the Sn-Y and Mg-Sn-Y systems was critically carried out by means of the CALPHAD（CALculation of PHAse Diagram） technique. In the Sn-Y system, the solution phases（liquid, bcc, bct and hcp） were described by the substitutional solution model. The compound Sn3Y5, which has a homogeneity range, was treated as the formula（Sn, Y）3（Sn, Y）2Y3 by a three-sublattice model in accordance with the site occupancies. In the Mg-Sn-Y system, the liquid phase was treated as the formula（Mg, Sn, Y, Mg2Sn） using an associated solution model, and bcc, bct and hcp were treated as the formula（Mg, Sn, Y）. The compound Sn3Y5 was treated as the formula（Sn, Y, Mg）3（Sn, Y, Mg）2Y3. The ternary compound MgSnY was treated as stoichiometric compound. A set of self-consistent thermodynamic parameters of the Mg-Sn-Y system was obtained. The projection of the liquidus surfaces and the reaction scheme of the Mg-Sn-Y system were predicted.展开更多
The Fe-Gd and Co-Fe-Gd systems were optimized by means of the CALPHAD （CALculation of PHAse Diagram） technique. The solution phases, liquid, bcc, fcc and hcp, were described by the substitutional solution model. For...The Fe-Gd and Co-Fe-Gd systems were optimized by means of the CALPHAD （CALculation of PHAse Diagram） technique. The solution phases, liquid, bcc, fcc and hcp, were described by the substitutional solution model. For the Fe-Gd system, the compounds Fe23Gd6,Fe3Gd and Fe2Gd with no solubility ranges were treated as stoichiometric compounds. According to the CaCu5-type structure of the intermetallic compounds Fe17Gd2,it was reasonable to adopt a three-sulattice model （Fe2,Gd）Gd2Fe15 in the Fe-Gd system, and this model was also adopted as （Co2,Fe2,Gd）（Co2,Gd）2（Co,Fe）15 to describe the compounds （Co,Fe）17Gd2 and （Co,Fe）5Gd in the Co-Fe-Gd ternary system. The other compounds were treated as the line compounds （Co,Fe）mGdn and no ternary compound had been reported in the Co-Fe-Gd system. The thermodynamic description of the Co-Fe and Co-Gd system were taken from literatures. A self-consistent thermodynamic description of the Co-Fe-Gd system was obtained.展开更多
New experimental measurements of the phase diagram and the mixing enthalpy of liquid phase along with the previous experimental data were used in a reassessment of the Ni–Ga system. A set of self-consistent thermodyn...New experimental measurements of the phase diagram and the mixing enthalpy of liquid phase along with the previous experimental data were used in a reassessment of the Ni–Ga system. A set of self-consistent thermodynamic parameters of the Ni–Ga system is obtained using the calculation of phase diagram (CALPHAD) technique, and the available phase diagram and thermodynamic data are reproduced well within experimental error limits. Some noticeable improvements are obtained in the present work compared with the previous assessment: (1) the calculated Ga-rich liquidus is more reasonable; (2) Ni<sub>3</sub>Ga<sub>7</sub> is adopted as the most Ga-rich compound rather than NiGa<sub>4</sub>; (3) the Ni<sub>5</sub>Ga<sub>3</sub> phase is treated as the nonstoichiometric compound with consideration of its narrow homogeneity range; (4) the phase transformation between B8<sub>1.5</sub>_Ni<sub>3</sub>Ga<sub>2</sub> and Ni<sub>13</sub>Ga<sub>9</sub> is considered instead of treating them as Ni<sub>3</sub>Ga<sub>2</sub> phase simply; (5) the latest experimental data of mixing enthalpy for the liquid phase are adopted. The present study can be used as a basis for the development of a thermodynamic database of the Ni-based semiconductor alloy systems.展开更多
基金Project(51271027)supported by the National Natural Science Foundation of ChinaProject(T201308)supported by Shenzhen Key Laboratory of Special Functional Materials of Shenzhen University,China
文摘On the basis of the experimental data of phase equilibria and thermochemical properties available from literatures, a critical assessment for the Ni?Yb binary system was carried out using the CALPHAD (calculation of phase diagrams) method. The liquid phase is modeled as the associate model with the constituent species Ni, Yb and YbNi3, owing to the sharp change of the enthalpy of mixing of liquid phase at the composition of around 25% Yb (mole fraction). The terminal solid solutions FCC_A1 (Ni/Yb) and BCC_A2 (Yb) are described by the substitutional solution model with the Redlich?Kister polynomial. The intermetallic compounds, Yb2Ni17, YbNi5, YbNi3, YbNi2, α-YbNi and β-YbNi, are treated as strict stoichiometric compounds, since there are no noticeable homogeneity ranges reported for these compounds. A set of self-consistent thermodynamic parameters for the Ni?Yb binary system are obtained. According to the presently assessed results, the thermochemical properties and the phase boundary data can be well reproduced.
基金This work was financially supported by the National Natural Science Foundation of China (Nos. 50471095 and 50271008).
文摘As an example of the La-Mg-Y system, the method how to set up the themaodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases （liquid, body-centered cubic, face-centered cubic, hexagonal close-packed and double hexagonal close-packed） were modeled with the Redlich-Kister equation. The compound energy model has been used to describe the thermodynamic functions of the intermetallic compounds in the La-Mg-Y systems. The compounds Mg2Y, Mg24Y5, Mg12La, Mg17La2, Mg41Las, Mg3La and Mg2La in the La-Mg-Y system were treated as the formulae （Mg,Y）2（La,Mg,Y）, Mg24（La,Mg,Y）4Y, Mg12（La, Y）, Mg17（La,Y）2, Mg41（La,Y）5, Mg3（La,Mg,Y） and Mg2（La, Y）, respectively. A model （La, Mg,Y）0.5（La,Mg,Y）0.5 was applied to describe the compound MgM formed by MgLa and MgY in order to cope with the order-disorder transition between body-centered cubic solution （A2） and MgM with CsCl-type structure （B2） in the La-Mg-Y system. The Gibbs energies of individual phases were optimized in the La-Mg, La-Y and La-Mg-Y systems by CALPHAD technique. The projection of the liquidus surfaces for the La-Mg-Y system was predicted. The Mg-based alloys database including 36 binary and 15 ternary systems formed by Mg, Al, Cu, Ni, Mn, Zn and rare earth elements was set up in SGTE standard.
基金supported by Key Project Foundation of Natural Science of Anhui Education Committee (KJ2008A068)Foundation of Nature Science of Hefei University (08KY019ZR)
文摘The Gibbs energies of liquid phases in the LaI3-MI （M= Na, K, Cs） systems were described by the modified quasi-chemical model. From the measured phase equilibrium data of these binary systems, a set of thermodynamic functions were optimized by using the CAL- PHAD technique. The enthalpy of mixing and the interaction parameter of the liquid phase were predicted from known data for the LaI3-MI systems.
基金the National Key Research and Development Program of China(No.2016YFB0701201)the National Natural Science Foundation of China(No.52071011)for the financial supports.
文摘Based on the available experimental phase equilibrium relations and aging precipitation sequences,the Mg–Gd–Y ternary system has been thermodynamically re-assessed by means of CALPHAD technique.To simulate the experimentally reported aging precipitation sequence,α(Mg)_(SS)(supersaturated)→GP zones(D019-type,metastable)→β’-Mg_(7)Gd(c-bco,metastable)→β_(1)-Mg_(3)Gd(fcc,metastable)→β-Mg_(5)Gd(fcc,stable)near the Mg–Gd side,andα(Mg)SS(supersaturated)→β’-Mg_(7)Y(c-bco,metastable)→β-Mg_(24)Y_(5)(bcc,stable)near the Mg–Y side,the effective nucleation driving forces obtained by deducting the nucleation resistances from the thermodynamic driving forces are calculated and analyzed.Two metastable components,GP zones(D019-type)andβ’(c-bco)ordered fromα(Mg)_(SS),do not exist in the stable equilibrium phase diagram but appear in the annealing process of typical alloys.The Redlich–Kister equations are adopted to describe three solution phases,Liquid,HCP_A3 and BCC_A2.The intermediate compounds Mg_(2)Y,Mg_(24)Y_(5),Mg_(2)Gd,Mg_(3)Gd and Mg_(5)Gd are expressed by the formulas of(Mg,Y)_(2/3)(Gd,Mg,Y)_(1/3),Mg_(24/29)(Gd,Mg,Y)_(4/29)Y1/29,(Gd,Mg)_(2/3)(Gd,Mg,Y)_(1/3),(Gd,Mg)_(3/4)(Gd,Mg,Y)_(1/4)and Mg_(5/6)(Gd,Mg,Y)_(1/6),respectively.In particular,the two-sublattice models(Gd,Mg,Y)_(1/2)(Gd,Mg,Y)_(1/2),(Gd,Mg,Y)_(3/4)(Gd,Mg,Y)_(1/4)and(Gd,Mg,Y)_(7/8)(Gd,Mg,Y)_(1/8)have been respectively used to describe the stable Mg(Gd,Y)(BCC_B2)alloy compound as well as the metastable GP zones(D019-type)andβ’(c-bco)phase,in order to cope with the order-disorder transitions.A set of self-consistent thermodynamic parameters has been obtained to ensure the thermodynamic calculations well consistent with the reported experimental data,containing not only the stable equilibrium phase diagram but also the aging precipitation sequence.
基金Project supported by National Natural Science Foundation of China(NSFC)(51171017,51371029)the National High Technology Research and Development Program of China(2013AA031601)
文摘The thermodynamic optimization of the Sn-Y and Mg-Sn-Y systems was critically carried out by means of the CALPHAD（CALculation of PHAse Diagram） technique. In the Sn-Y system, the solution phases（liquid, bcc, bct and hcp） were described by the substitutional solution model. The compound Sn3Y5, which has a homogeneity range, was treated as the formula（Sn, Y）3（Sn, Y）2Y3 by a three-sublattice model in accordance with the site occupancies. In the Mg-Sn-Y system, the liquid phase was treated as the formula（Mg, Sn, Y, Mg2Sn） using an associated solution model, and bcc, bct and hcp were treated as the formula（Mg, Sn, Y）. The compound Sn3Y5 was treated as the formula（Sn, Y, Mg）3（Sn, Y, Mg）2Y3. The ternary compound MgSnY was treated as stoichiometric compound. A set of self-consistent thermodynamic parameters of the Mg-Sn-Y system was obtained. The projection of the liquidus surfaces and the reaction scheme of the Mg-Sn-Y system were predicted.
基金Project supported by National Natural Science Foundation of China(50934011,50971027)
文摘The Fe-Gd and Co-Fe-Gd systems were optimized by means of the CALPHAD （CALculation of PHAse Diagram） technique. The solution phases, liquid, bcc, fcc and hcp, were described by the substitutional solution model. For the Fe-Gd system, the compounds Fe23Gd6,Fe3Gd and Fe2Gd with no solubility ranges were treated as stoichiometric compounds. According to the CaCu5-type structure of the intermetallic compounds Fe17Gd2,it was reasonable to adopt a three-sulattice model （Fe2,Gd）Gd2Fe15 in the Fe-Gd system, and this model was also adopted as （Co2,Fe2,Gd）（Co2,Gd）2（Co,Fe）15 to describe the compounds （Co,Fe）17Gd2 and （Co,Fe）5Gd in the Co-Fe-Gd ternary system. The other compounds were treated as the line compounds （Co,Fe）mGdn and no ternary compound had been reported in the Co-Fe-Gd system. The thermodynamic description of the Co-Fe and Co-Gd system were taken from literatures. A self-consistent thermodynamic description of the Co-Fe-Gd system was obtained.
基金financially supported by the National Natural Science Foundation of China(Nos.50934011 and51274034)the Fundamental Research Funds for the Central Universities(No.FRF-SD-12-010A)
文摘New experimental measurements of the phase diagram and the mixing enthalpy of liquid phase along with the previous experimental data were used in a reassessment of the Ni–Ga system. A set of self-consistent thermodynamic parameters of the Ni–Ga system is obtained using the calculation of phase diagram (CALPHAD) technique, and the available phase diagram and thermodynamic data are reproduced well within experimental error limits. Some noticeable improvements are obtained in the present work compared with the previous assessment: (1) the calculated Ga-rich liquidus is more reasonable; (2) Ni<sub>3</sub>Ga<sub>7</sub> is adopted as the most Ga-rich compound rather than NiGa<sub>4</sub>; (3) the Ni<sub>5</sub>Ga<sub>3</sub> phase is treated as the nonstoichiometric compound with consideration of its narrow homogeneity range; (4) the phase transformation between B8<sub>1.5</sub>_Ni<sub>3</sub>Ga<sub>2</sub> and Ni<sub>13</sub>Ga<sub>9</sub> is considered instead of treating them as Ni<sub>3</sub>Ga<sub>2</sub> phase simply; (5) the latest experimental data of mixing enthalpy for the liquid phase are adopted. The present study can be used as a basis for the development of a thermodynamic database of the Ni-based semiconductor alloy systems.
