A method based on the semi-empirical Miedema model and a geometrical model was used to study the glass forming abili-ties （GFA） and the amorphous forming ranges of Al-Fe-Nd-Zr system and its constituent ternary syst...A method based on the semi-empirical Miedema model and a geometrical model was used to study the glass forming abili-ties （GFA） and the amorphous forming ranges of Al-Fe-Nd-Zr system and its constituent ternary systems. The amorphous forming composition ranges were analyzed based on different criteria such asΔGam-ss and PHSS （PHSS=ΔHchem （ΔSC/R）（ΔSσ/R）） for Al-Fe-Nd system. The predicted amorphous forming range was in good agreement with the experimental results. The results showed that the criterion ofΔGam-ss was more accurate, and agreed well with the experiment results. The Gibbs free energy differenceΔGam-ss and pa-rameter PHSS were then used to predict the amorphous forming composition range for the rest of the constitutive ternary systems of Al-Fe-Nd-Zr. In addition, the amorphous forming composition ranges of the （Al-Fe-Zr）100-xNdx （x=50, 60, 70） systems were predicted byΔGam-ss and the modified parameter PHSS. The Gibbs free energy of Al10（Fe1-xZrx）30Nd60 were also calculated. The GFA parameter PHSS indicated that the composition with the highest GFA was Al33.5Fe13.5Zr3Nd50 for the （Al-Fe-Zr）50Nd50 system, Al28.8Fe10Zr1.2Nd60 for the （Al-Fe-Zr）40Nd60 system and Al22.8Fe6.9Zr0.3Nd70 for the （Al-Fe-Zr）30Nd70 system, and the results suggested that those alloys with high content of Al had higher GFA. The appropriate content of neodymium and zirconium resulted in the lower value of PHSS and increased the GFA obviously.展开更多
合金形成焓是确定合金的稳定性及其非晶形成能力的重要因素。采用Miedema理论和几何外推模型相结合,预测了Al-Cu-RE(RE=La^Lu)体系液态合金整个成分范围的混合焓。计算结果表明:Al-Cu-RE三元体系的混合焓比Al-Cu二元合金的混合焓更负,...合金形成焓是确定合金的稳定性及其非晶形成能力的重要因素。采用Miedema理论和几何外推模型相结合,预测了Al-Cu-RE(RE=La^Lu)体系液态合金整个成分范围的混合焓。计算结果表明:Al-Cu-RE三元体系的混合焓比Al-Cu二元合金的混合焓更负,稀土元素与Al、Cu之间的化学势差对混合焓的贡献起主要作用。当铝与稀土元素含量相同时,随着铜含量的减少,合金混合焓越来越负,从而表明在Al-Cu合金中加入稀土元素有利于Al-Cu-RE三元合金的形成。同时较负的混合焓是合金体系易于非晶化的重要条件之一,也说明Al-Cu-RE三元体系非晶形成能力较强。计算了Al8Cu4RE和Al Cu RE等三元化合物的形成焓,计算得到的Al Cu RE的形成焓比相应的Al8Cu4RE的形成焓要负,说明Al Cu RE更稳定;同时计算了金属间化合物Al(Cu1-xREx)3、Al(Cu1-xREx)、Al2(Cu1-xREx)的形成焓随稀土含量变化趋势。计算结果为Al-Cu-RE体系非晶形成的成分设计和相关性能研究提供了重要的热力学数据。展开更多
Amorphous structure generated by high-energy ball miller(BM)is often used as a precursor for generating nanocomposites through controlled devitrification.The amorphous forming composition range of ternary Al-Cu-Zr sys...Amorphous structure generated by high-energy ball miller(BM)is often used as a precursor for generating nanocomposites through controlled devitrification.The amorphous forming composition range of ternary Al-Cu-Zr system was calculated using the extended Miedema’s semiempirical model.Eleven compositions of Al-Cu-Zr system showed a wide range of negative enthalpy of mixing(-ΔH^(mix))and amorphization(-ΔH^(amor))among the constituent elements was selected for synthesis by BM.They yielded either nanocomposites of partial amorphous and crystalline structure or no amorphous phase at all in the as-milled condition.The Al_(88)Cu_(6)Zr_(6) alloy with relatively small negativeΔH^(mix)(-0.4 kJ/mol)andΔH^(amor)(-14.8 kJ/mol)became completely amorphous after 120 h of milling.展开更多
A calculation formula of ln γ i 0 for solute element i in liquid alloys was derived by use of free volume theory and Miedema formation enthalpy model. The values of ln γ i 0 of solute elements in liqui...A calculation formula of ln γ i 0 for solute element i in liquid alloys was derived by use of free volume theory and Miedema formation enthalpy model. The values of ln γ i 0 of solute elements in liquid copper at 1273 K were obtained. The results obtained show that the coincidence rate of sign (positive or negative) was 90% for the calculated and experimental values, which were basically in the same magnitude.展开更多
As the sulfide ore deposits become less economical and environmental viable as a source of nickel,increasing attention is being paid to the laterite ores.But in the pyrometallurgical process of laterite,more efforts s...As the sulfide ore deposits become less economical and environmental viable as a source of nickel,increasing attention is being paid to the laterite ores.But in the pyrometallurgical process of laterite,more efforts should be paid to control the reduction of iron oxide in order to get high nickel-content nickeliferous product.For these reasons,equilibrium condition of iron oxide when laterite ore was selectively reduced by CO2/CO,H2O/H2 and CO2/H2 was studied from the perspective of iron activity with an assumption that the activities of Fe O and Fe3O4 equal 1 in this work,and it well accounts for the inescapability of Fe metallization.Activity coefficient of iron in Ni-Fe binary solid alloy was calculated by Miedema model based on the known thermodynamics datum filed.According to Raoult＇s law,the relationship among the Fe/Ni ratio,reduction temperature and reduction gas composition was calculated when laterite ore was selectively reduced by the three different reduction systems.The calculation result was discussed and also compared with the experimental result.The trend of metal iron content in the reduction product of laterite ore varying with temperature and gas composition was well predicted by the calculation result.展开更多
基金Project supported by the National Natural Science Foundation of China(51061004)Science Foundation of Guangxi Education Department(2013YB377)
文摘A method based on the semi-empirical Miedema model and a geometrical model was used to study the glass forming abili-ties （GFA） and the amorphous forming ranges of Al-Fe-Nd-Zr system and its constituent ternary systems. The amorphous forming composition ranges were analyzed based on different criteria such asΔGam-ss and PHSS （PHSS=ΔHchem （ΔSC/R）（ΔSσ/R）） for Al-Fe-Nd system. The predicted amorphous forming range was in good agreement with the experimental results. The results showed that the criterion ofΔGam-ss was more accurate, and agreed well with the experiment results. The Gibbs free energy differenceΔGam-ss and pa-rameter PHSS were then used to predict the amorphous forming composition range for the rest of the constitutive ternary systems of Al-Fe-Nd-Zr. In addition, the amorphous forming composition ranges of the （Al-Fe-Zr）100-xNdx （x=50, 60, 70） systems were predicted byΔGam-ss and the modified parameter PHSS. The Gibbs free energy of Al10（Fe1-xZrx）30Nd60 were also calculated. The GFA parameter PHSS indicated that the composition with the highest GFA was Al33.5Fe13.5Zr3Nd50 for the （Al-Fe-Zr）50Nd50 system, Al28.8Fe10Zr1.2Nd60 for the （Al-Fe-Zr）40Nd60 system and Al22.8Fe6.9Zr0.3Nd70 for the （Al-Fe-Zr）30Nd70 system, and the results suggested that those alloys with high content of Al had higher GFA. The appropriate content of neodymium and zirconium resulted in the lower value of PHSS and increased the GFA obviously.
文摘合金形成焓是确定合金的稳定性及其非晶形成能力的重要因素。采用Miedema理论和几何外推模型相结合,预测了Al-Cu-RE(RE=La^Lu)体系液态合金整个成分范围的混合焓。计算结果表明:Al-Cu-RE三元体系的混合焓比Al-Cu二元合金的混合焓更负,稀土元素与Al、Cu之间的化学势差对混合焓的贡献起主要作用。当铝与稀土元素含量相同时,随着铜含量的减少,合金混合焓越来越负,从而表明在Al-Cu合金中加入稀土元素有利于Al-Cu-RE三元合金的形成。同时较负的混合焓是合金体系易于非晶化的重要条件之一,也说明Al-Cu-RE三元体系非晶形成能力较强。计算了Al8Cu4RE和Al Cu RE等三元化合物的形成焓,计算得到的Al Cu RE的形成焓比相应的Al8Cu4RE的形成焓要负,说明Al Cu RE更稳定;同时计算了金属间化合物Al(Cu1-xREx)3、Al(Cu1-xREx)、Al2(Cu1-xREx)的形成焓随稀土含量变化趋势。计算结果为Al-Cu-RE体系非晶形成的成分设计和相关性能研究提供了重要的热力学数据。
文摘Amorphous structure generated by high-energy ball miller(BM)is often used as a precursor for generating nanocomposites through controlled devitrification.The amorphous forming composition range of ternary Al-Cu-Zr system was calculated using the extended Miedema’s semiempirical model.Eleven compositions of Al-Cu-Zr system showed a wide range of negative enthalpy of mixing(-ΔH^(mix))and amorphization(-ΔH^(amor))among the constituent elements was selected for synthesis by BM.They yielded either nanocomposites of partial amorphous and crystalline structure or no amorphous phase at all in the as-milled condition.The Al_(88)Cu_(6)Zr_(6) alloy with relatively small negativeΔH^(mix)(-0.4 kJ/mol)andΔH^(amor)(-14.8 kJ/mol)became completely amorphous after 120 h of milling.
文摘A calculation formula of ln γ i 0 for solute element i in liquid alloys was derived by use of free volume theory and Miedema formation enthalpy model. The values of ln γ i 0 of solute elements in liquid copper at 1273 K were obtained. The results obtained show that the coincidence rate of sign (positive or negative) was 90% for the calculated and experimental values, which were basically in the same magnitude.
基金Project(2012CB722805)supported by the National Basic Research Program of China
文摘As the sulfide ore deposits become less economical and environmental viable as a source of nickel,increasing attention is being paid to the laterite ores.But in the pyrometallurgical process of laterite,more efforts should be paid to control the reduction of iron oxide in order to get high nickel-content nickeliferous product.For these reasons,equilibrium condition of iron oxide when laterite ore was selectively reduced by CO2/CO,H2O/H2 and CO2/H2 was studied from the perspective of iron activity with an assumption that the activities of Fe O and Fe3O4 equal 1 in this work,and it well accounts for the inescapability of Fe metallization.Activity coefficient of iron in Ni-Fe binary solid alloy was calculated by Miedema model based on the known thermodynamics datum filed.According to Raoult＇s law,the relationship among the Fe/Ni ratio,reduction temperature and reduction gas composition was calculated when laterite ore was selectively reduced by the three different reduction systems.The calculation result was discussed and also compared with the experimental result.The trend of metal iron content in the reduction product of laterite ore varying with temperature and gas composition was well predicted by the calculation result.
