Pd80+xSi20-x (x=0,1,and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increas...Pd80+xSi20-x (x=0,1,and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content,the glass transition temperature Tg,the initial crystallization temperature Tx and the onset crystalliza-tion temperature Tp of Pd-Si binary glassy alloys increase. Moreover,the super-cooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability,which can be greatly improved by fluxing treatment.展开更多
The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kine...The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams, which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.展开更多
The parameters of embedded atom method for elements Ce, Th and Yb were determined by fitting the lattice constants, the cohesive energy, the monovacancy formation energy and the bulk modulus of elements. The alloy pot...The parameters of embedded atom method for elements Ce, Th and Yb were determined by fitting the lattice constants, the cohesive energy, the monovacancy formation energy and the bulk modulus of elements. The alloy potential was taken as the form of Johnson′s. The formation enthalpies of Th-Ce, Th-Yb and Ce-Yb binary alloys systems and Ce-Th-Yb ternary alloy were calculated with the present embedded atom potentials. The calculations for binary alloys are in good agreement with the results calculated with Miedema′s theory. As for the ternary alloy, the calculated formation enthalpies are in good agreement with those extrapolated from the formation enthalpies of constitutive binary alloys by Toop′s model.展开更多
A new method of revising activity values has been derived based on the so called correction factor function for binary alloys with a large difference between two components. The correction factor is a function of phys...A new method of revising activity values has been derived based on the so called correction factor function for binary alloys with a large difference between two components. The correction factor is a function of physical properties formed by the difference of two components. Its absolute value increases with the enhancement of the difference in the character of components. It can be either positive or negative and the rules for selecting the sign of correction factor have been analyzed. Results are in good agreement with the experimental values.展开更多
It is found that the anomalous eutectics can be separated on macroscopic scale by flow caused by electromagnetic stirring, and the separated phase is the leading faceted phase with the solution entropy over 23 J/(mol&...It is found that the anomalous eutectics can be separated on macroscopic scale by flow caused by electromagnetic stirring, and the separated phase is the leading faceted phase with the solution entropy over 23 J/(mol·K). By using this technology, a new kind of composite pipe and gear with good abrasive properties were made without adding any reinforced particles. Emphases were paid on the researches about formation mechanism of separated eutectic and abrasive property of the composite pipe or gear. The result shows that the entropy of solution controlling the eutectic microstructure is also valid and useful as a criterion of separated eutectic, and the kind and its chemical scope of the off-eutectic used to make composite can be calculated according to this theory.展开更多
用 X 射线、电子衍射及透射电镜观察等方法研究了 Fe-27Mo 及 Fe-16Mo 合金的时效析出行为.结果发现,在873～1453K 时效时.时效初期,两种合金中均有一种新的过渡相——R 相析出.随时效进行,过渡相 R 将向平衡相μ(1213～1453K)或 Laves(...用 X 射线、电子衍射及透射电镜观察等方法研究了 Fe-27Mo 及 Fe-16Mo 合金的时效析出行为.结果发现,在873～1453K 时效时.时效初期,两种合金中均有一种新的过渡相——R 相析出.随时效进行,过渡相 R 将向平衡相μ(1213～1453K)或 Laves(873～1213K)转度.过渡相 R 为菱形点阵,点阵常数α=0.8977nm,α=74.4°,其 Mo 含量为48%,呈棒状或块状形态析出.时效初期由于过渡相 R 的析出引起合金硬化.展开更多
基金the National Basic Research Program of China (Grant No. 2007CB613905)the National Natural Science Foundation of China (Grant Nos. 50671050 and 50431030)
文摘Pd80+xSi20-x (x=0,1,and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content,the glass transition temperature Tg,the initial crystallization temperature Tx and the onset crystalliza-tion temperature Tp of Pd-Si binary glassy alloys increase. Moreover,the super-cooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability,which can be greatly improved by fluxing treatment.
基金Financial supports by the NSFC(China)under the research projects(No.50071058 and No.59725101)by the CAS(China)-CNR(Italy)under an international collaboration agreement are gratefully acknowledged.
文摘The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams, which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.
文摘The parameters of embedded atom method for elements Ce, Th and Yb were determined by fitting the lattice constants, the cohesive energy, the monovacancy formation energy and the bulk modulus of elements. The alloy potential was taken as the form of Johnson′s. The formation enthalpies of Th-Ce, Th-Yb and Ce-Yb binary alloys systems and Ce-Th-Yb ternary alloy were calculated with the present embedded atom potentials. The calculations for binary alloys are in good agreement with the results calculated with Miedema′s theory. As for the ternary alloy, the calculated formation enthalpies are in good agreement with those extrapolated from the formation enthalpies of constitutive binary alloys by Toop′s model.
基金Financial support of this research by the National Natural Sci-ence Foundation of China under Grants 50074013 and 59774027and Huo Ying-Dong Education Foundation is gratefully acknowl-edged. Thanks are furthermore due to Chinese-Austrian Scientific Techni
文摘A new method of revising activity values has been derived based on the so called correction factor function for binary alloys with a large difference between two components. The correction factor is a function of physical properties formed by the difference of two components. Its absolute value increases with the enhancement of the difference in the character of components. It can be either positive or negative and the rules for selecting the sign of correction factor have been analyzed. Results are in good agreement with the experimental values.
文摘It is found that the anomalous eutectics can be separated on macroscopic scale by flow caused by electromagnetic stirring, and the separated phase is the leading faceted phase with the solution entropy over 23 J/(mol·K). By using this technology, a new kind of composite pipe and gear with good abrasive properties were made without adding any reinforced particles. Emphases were paid on the researches about formation mechanism of separated eutectic and abrasive property of the composite pipe or gear. The result shows that the entropy of solution controlling the eutectic microstructure is also valid and useful as a criterion of separated eutectic, and the kind and its chemical scope of the off-eutectic used to make composite can be calculated according to this theory.
文摘用 X 射线、电子衍射及透射电镜观察等方法研究了 Fe-27Mo 及 Fe-16Mo 合金的时效析出行为.结果发现,在873～1453K 时效时.时效初期,两种合金中均有一种新的过渡相——R 相析出.随时效进行,过渡相 R 将向平衡相μ(1213～1453K)或 Laves(873～1213K)转度.过渡相 R 为菱形点阵,点阵常数α=0.8977nm,α=74.4°,其 Mo 含量为48%,呈棒状或块状形态析出.时效初期由于过渡相 R 的析出引起合金硬化.
