Antioxidation effects on Sm （Co, Cu, Fe, Zr）z-sintered magnets treated by different methods were studied through TGA and DTA. Microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets was analyzed through SEM and EDS...Antioxidation effects on Sm （Co, Cu, Fe, Zr）z-sintered magnets treated by different methods were studied through TGA and DTA. Microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets was analyzed through SEM and EDS. The results indicate that the antioxidation effect of the alloy powder treated in silane solution is better than that of the other methods. The alloy powders treated in stearic acid （SA） solution and polymethyl methacrylate （PMMA） solution can prevent powders from oxidation for a short period of time. Silane solution is not suitable for metal injection molding （MIM） because it severely damages the magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets. SA solution can not only prevent powders from oxidizing in MIM, but also does not damage magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z magnets. The oxygen content of Sm（Co, Cu, Fe, Zr）z-sintered magnets by MIM is 3300μg·g^-1.展开更多
A new series of Sm-Cu-Ni-Al bulk metallic glasses were prepared by suction casting. Their glass-forming ability and thermal stability were investigated by X-ray diffraction (XRD) and differential scanning calorimetry ...A new series of Sm-Cu-Ni-Al bulk metallic glasses were prepared by suction casting. Their glass-forming ability and thermal stability were investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results of DSC indicate that the alloy components strongly affect the widths of supercooled liquid region (ΔT_x=T_x-T_g onset). The widths of supercooled liquid region for Sm_ 70-xCu_xNi_ 10Al_ 20 (x=12.5, 15.0, 17.5), Sm_ 65-xCu_ 15Ni_xAl_ 20 (x=8, 10, 12) and Sm_ 75-xCu_ 15Ni_ 10Al_x (x=15, 20, 25) increase first and then decrease with the increase of x atomic fraction. And Sm_ 55Cu_ 15Ni_ 10Al_ 20 alloy was found to be with the largest width and it can be cast into bulk metallic glass with up to 3 mm in diameter. The glass-forming ability of the alloys was explained in terms of Miedema′s theory, electronegativity difference and atomic size parameter of the amorphous alloys.展开更多
Ternary Sm-based Sm-Al-Co alloys at specific compositions designed using an e/a- and cluster-related criteria exhibit high glass forming abilities and form bulk glassy rods of 3 mm in diameter by a copper mold suction...Ternary Sm-based Sm-Al-Co alloys at specific compositions designed using an e/a- and cluster-related criteria exhibit high glass forming abilities and form bulk glassy rods of 3 mm in diameter by a copper mold suction-casting method. Four composi- tions of bulk metallic glasses (BMGs) are Sm50Al25Co25, Sm52Al24Co24, Sm54Al23Co23 and Sm56Al22Co22, which all satisfy a constant conduction electron concentration of 1.5. Among them, the BMG exhibiting the largest reduced glass transition temperature (Trg) is Sm50Al25Co25, which reaches 0.648. The glass transition temperature Tg and the onset crystallization temperature Tx of this alloy are respectively 579 and 640 K at a heating rate of 20 K/min.展开更多
Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semicon...Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semiconducting range, whereas it vibrates similarly to a sine wave in the superconducting range, which is ascribed to the existence of oxygen vacancies and the function of breathing modes of Bi（Pb）O6. The temperature dependence of resistivity indicates that the electrical property of the samples is connected sensitively with the crystal structures. Raman spectra show that the specimen becomes disorder when x increases, and the critical temperature To depends not only on the deformation potential of the soft A19 mode derived from the Bi（Pb）O6 rigid rotation, but also on the energy shift of the mode.展开更多
基金Project supported by Specialized Research Fundfor the Doctoral Programof Higher Education (20040008015)ProgramforNew Century Excellent Talents in University (NCET)
文摘Antioxidation effects on Sm （Co, Cu, Fe, Zr）z-sintered magnets treated by different methods were studied through TGA and DTA. Microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets was analyzed through SEM and EDS. The results indicate that the antioxidation effect of the alloy powder treated in silane solution is better than that of the other methods. The alloy powders treated in stearic acid （SA） solution and polymethyl methacrylate （PMMA） solution can prevent powders from oxidation for a short period of time. Silane solution is not suitable for metal injection molding （MIM） because it severely damages the magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets. SA solution can not only prevent powders from oxidizing in MIM, but also does not damage magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z magnets. The oxygen content of Sm（Co, Cu, Fe, Zr）z-sintered magnets by MIM is 3300μg·g^-1.
文摘A new series of Sm-Cu-Ni-Al bulk metallic glasses were prepared by suction casting. Their glass-forming ability and thermal stability were investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results of DSC indicate that the alloy components strongly affect the widths of supercooled liquid region (ΔT_x=T_x-T_g onset). The widths of supercooled liquid region for Sm_ 70-xCu_xNi_ 10Al_ 20 (x=12.5, 15.0, 17.5), Sm_ 65-xCu_ 15Ni_xAl_ 20 (x=8, 10, 12) and Sm_ 75-xCu_ 15Ni_ 10Al_x (x=15, 20, 25) increase first and then decrease with the increase of x atomic fraction. And Sm_ 55Cu_ 15Ni_ 10Al_ 20 alloy was found to be with the largest width and it can be cast into bulk metallic glass with up to 3 mm in diameter. The glass-forming ability of the alloys was explained in terms of Miedema′s theory, electronegativity difference and atomic size parameter of the amorphous alloys.
基金This work was financially supported by the National Natural Science Foundation of China (No.50401020, 50671018 and 50631010)the Provincial Science and Technology Foundation of Liaoning (No.20061067).
文摘Ternary Sm-based Sm-Al-Co alloys at specific compositions designed using an e/a- and cluster-related criteria exhibit high glass forming abilities and form bulk glassy rods of 3 mm in diameter by a copper mold suction-casting method. Four composi- tions of bulk metallic glasses (BMGs) are Sm50Al25Co25, Sm52Al24Co24, Sm54Al23Co23 and Sm56Al22Co22, which all satisfy a constant conduction electron concentration of 1.5. Among them, the BMG exhibiting the largest reduced glass transition temperature (Trg) is Sm50Al25Co25, which reaches 0.648. The glass transition temperature Tg and the onset crystallization temperature Tx of this alloy are respectively 579 and 640 K at a heating rate of 20 K/min.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10104013 and 50421201, and the National Basic Research Programme of China under Grant No 2006CB601003.
文摘Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semiconducting range, whereas it vibrates similarly to a sine wave in the superconducting range, which is ascribed to the existence of oxygen vacancies and the function of breathing modes of Bi（Pb）O6. The temperature dependence of resistivity indicates that the electrical property of the samples is connected sensitively with the crystal structures. Raman spectra show that the specimen becomes disorder when x increases, and the critical temperature To depends not only on the deformation potential of the soft A19 mode derived from the Bi（Pb）O6 rigid rotation, but also on the energy shift of the mode.
