The effect of niobium on glass-formation ability and soft magnetic properties were studied in Fe-Gd-B glassy alloys. The glassy alloys exhibited high glass-formation ability when the element of Nb was added. Bulk glas...The effect of niobium on glass-formation ability and soft magnetic properties were studied in Fe-Gd-B glassy alloys. The glassy alloys exhibited high glass-formation ability when the element of Nb was added. Bulk glassy rod （Fe0.87Co0.13）68.5Gd3.5Nb3B25 with a diameter up to 3 mm was produced by copper mold casting. The size of the atom might play an important role in increasing glass-formation ability. The coercive force of glassy （Fe0.87Co0.13）71.5.xGd3.sNbxB25 （x=1.2, 1.5, 2, 2.5, 3, 4） alloys decreased after the addition of niobium element and was in the range of 1.5-2.9 A/m. The permeability spectrum of （Fe0.87Co0.13）70.3Gd3.5Nb1.5B25 glassy ribbon showed that the relaxation frequency （f0） was 6.1 MHz.展开更多
This paper reviews the development of current research in bulk glassy alloys by focusing on the trigger point for the synthesis of the first bulk glassy alloys by the conventional mold casting method. This review cove...This paper reviews the development of current research in bulk glassy alloys by focusing on the trigger point for the synthesis of the first bulk glassy alloys by the conventional mold casting method. This review covers the background, discovery, characteristics, and applications of bulk glassy alloys, as well as recent topics regarding them. Applications of bulk glassy alloys have been expanding, particularly for Fe-based bulk glassy alloys, due to their unique properties, high glass-forming ability, and low cost. In the near future, the engineering importance of bulk glassy alloys is expected to increase steadily, and continuous interest in these novel metallic materials for basic science research is anticipated.展开更多
The effect of repeated melting of the mother ingot on the thermal stabilityof a Zr_(60)Al_+(15)Ni_(25) glassy alloy was investigated by differential scanning calorimetry(DSC). Experimental results indicate that after ...The effect of repeated melting of the mother ingot on the thermal stabilityof a Zr_(60)Al_+(15)Ni_(25) glassy alloy was investigated by differential scanning calorimetry(DSC). Experimental results indicate that after the repeated melting of the ingots at 1300 and 1580K, the glass transition temperature T_g increases from 686.4 to 690.7 and 696.8 K and the onsettemperature of crystallization T_x from 757.9 to 758.6 and 763.4 K, respectively, indicating thatthe thermal stability becomes higher after the repeated arc melting of the mother ingot and that itis more effective at higher temperature. Within the framework of structure heredity, the origin ofthe improvement of the thermal stability of Zr_(60)Al_+(15)Ni_(25) bulk glassy alloy is discussed.展开更多
The work functions before and after crystallization of two glassy alloys,Pd_(83.5)Si_(16.5) and Cu_(70)Ti_(30) have been measured by means of the con- tact potential difference method in the secondary electron field a...The work functions before and after crystallization of two glassy alloys,Pd_(83.5)Si_(16.5) and Cu_(70)Ti_(30) have been measured by means of the con- tact potential difference method in the secondary electron field at room temperature under 10^(-5) Pa vacuum.The results show that the work functions of both glassy alloys are higher than those of the corresponding crystalline alloys.展开更多
The non-isothermal and isothermal crystallization kinetics of Zr_（72.5）Al_（10）Fe_（17.5） glassy alloy was investigated using differential scanning calorimeter（DSC）.Under non-isothermal heating condition,the pri...The non-isothermal and isothermal crystallization kinetics of Zr_（72.5）Al_（10）Fe_（17.5） glassy alloy was investigated using differential scanning calorimeter（DSC）.Under non-isothermal heating condition,the primary phase in the initial crystallization is Zr_6Al_2Fe phase and the final crystallized products consist of Zr_6Al_2Fe,Zr_2Fe and a-Zr phases.The apparent activation energy for crystallization estimated using the Kissinger method is 342.1 ±8.1 kJ/mol.The local activation energy decreased with the increase in the crystallization volume fraction during nonisothermal crystallization.Under isothermal heating condition,the average Avrami exponent of about 2.76 implies a mainly diffusion-controlled three-dimensional growth with an increasing nucleation rate.The local activation energy for isothermal crystallization shows a different variation trend from that for nonisothermal crystallization,indicating different nucleation-and-growth mechanisms for the two crystallizaiton conditions.展开更多
The bulk glassy Cu 60 Zr 30 Ti 10 alloy with a diameter up to 4 mm and a length of 70 mm containing nanocrystalline phase was successfully developed by using copper mold casting method. The temperature interval of the...The bulk glassy Cu 60 Zr 30 Ti 10 alloy with a diameter up to 4 mm and a length of 70 mm containing nanocrystalline phase was successfully developed by using copper mold casting method. The temperature interval of the supercooled liquid region before crystallization is above 37 K. The glass transition temperature ( T g) and the reduced glass transition temperature ( T g/ T l) of the cast bulk glassy Cu 60 Zr 30 Ti 10 alloy are 713 K and 0.62. The cast bulk glassy alloy, which has high glassy forming ability, shows expected mechanical properties. The elastic modulus, yield strength, fracture strength and elongation including elastic elongation are 114 GPa, 1 785 MPa, 2 150 MPa and 3.3% respectively in compressive deformation, and 112 GPa, 1 780 MPa, 2 000 MPa and 1.9% respectively in tensile deformation. High resolution transmission electron microscope (HRTEM) and nano beam electron diffraction (NBED) studies indicate that the cast metallic bulk glassy Cu 60 Zr 30 Ti 10 alloy consists of nanocrystals with a size of 4 nm embedded in glassy matrix. The nanoparticle is identified as CuZr and has point space group symmetry of pm3m and its lattice parameter is a =0.3 262 nm . The nanocrystalline phase grew up to 10 nm upon annealing at 430 ℃ for 10 min and caused the alloy brittle.展开更多
基金Project supported by the National Natural Science Foundation of China (50471094)
文摘The effect of niobium on glass-formation ability and soft magnetic properties were studied in Fe-Gd-B glassy alloys. The glassy alloys exhibited high glass-formation ability when the element of Nb was added. Bulk glassy rod （Fe0.87Co0.13）68.5Gd3.5Nb3B25 with a diameter up to 3 mm was produced by copper mold casting. The size of the atom might play an important role in increasing glass-formation ability. The coercive force of glassy （Fe0.87Co0.13）71.5.xGd3.sNbxB25 （x=1.2, 1.5, 2, 2.5, 3, 4） alloys decreased after the addition of niobium element and was in the range of 1.5-2.9 A/m. The permeability spectrum of （Fe0.87Co0.13）70.3Gd3.5Nb1.5B25 glassy ribbon showed that the relaxation frequency （f0） was 6.1 MHz.
基金supported by Guangdong Innovative Research Team Program (2009010005)
文摘This paper reviews the development of current research in bulk glassy alloys by focusing on the trigger point for the synthesis of the first bulk glassy alloys by the conventional mold casting method. This review covers the background, discovery, characteristics, and applications of bulk glassy alloys, as well as recent topics regarding them. Applications of bulk glassy alloys have been expanding, particularly for Fe-based bulk glassy alloys, due to their unique properties, high glass-forming ability, and low cost. In the near future, the engineering importance of bulk glassy alloys is expected to increase steadily, and continuous interest in these novel metallic materials for basic science research is anticipated.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50071032)
文摘The effect of repeated melting of the mother ingot on the thermal stabilityof a Zr_(60)Al_+(15)Ni_(25) glassy alloy was investigated by differential scanning calorimetry(DSC). Experimental results indicate that after the repeated melting of the ingots at 1300 and 1580K, the glass transition temperature T_g increases from 686.4 to 690.7 and 696.8 K and the onsettemperature of crystallization T_x from 757.9 to 758.6 and 763.4 K, respectively, indicating thatthe thermal stability becomes higher after the repeated arc melting of the mother ingot and that itis more effective at higher temperature. Within the framework of structure heredity, the origin ofthe improvement of the thermal stability of Zr_(60)Al_+(15)Ni_(25) bulk glassy alloy is discussed.
文摘The work functions before and after crystallization of two glassy alloys,Pd_(83.5)Si_(16.5) and Cu_(70)Ti_(30) have been measured by means of the con- tact potential difference method in the secondary electron field at room temperature under 10^(-5) Pa vacuum.The results show that the work functions of both glassy alloys are higher than those of the corresponding crystalline alloys.
基金Funded by the National Natural Science Foundation of China(No.51401053)the China Postdoctoral Science Foundation(No.2015T80676)+1 种基金the Natural Science Foundation of Fujian Province(No.2014J05053)the Postdoctoral Scientific Research Foundation of Fuzhou University(No.0180-601017)
文摘The non-isothermal and isothermal crystallization kinetics of Zr_（72.5）Al_（10）Fe_（17.5） glassy alloy was investigated using differential scanning calorimeter（DSC）.Under non-isothermal heating condition,the primary phase in the initial crystallization is Zr_6Al_2Fe phase and the final crystallized products consist of Zr_6Al_2Fe,Zr_2Fe and a-Zr phases.The apparent activation energy for crystallization estimated using the Kissinger method is 342.1 ±8.1 kJ/mol.The local activation energy decreased with the increase in the crystallization volume fraction during nonisothermal crystallization.Under isothermal heating condition,the average Avrami exponent of about 2.76 implies a mainly diffusion-controlled three-dimensional growth with an increasing nucleation rate.The local activation energy for isothermal crystallization shows a different variation trend from that for nonisothermal crystallization,indicating different nucleation-and-growth mechanisms for the two crystallizaiton conditions.
文摘The bulk glassy Cu 60 Zr 30 Ti 10 alloy with a diameter up to 4 mm and a length of 70 mm containing nanocrystalline phase was successfully developed by using copper mold casting method. The temperature interval of the supercooled liquid region before crystallization is above 37 K. The glass transition temperature ( T g) and the reduced glass transition temperature ( T g/ T l) of the cast bulk glassy Cu 60 Zr 30 Ti 10 alloy are 713 K and 0.62. The cast bulk glassy alloy, which has high glassy forming ability, shows expected mechanical properties. The elastic modulus, yield strength, fracture strength and elongation including elastic elongation are 114 GPa, 1 785 MPa, 2 150 MPa and 3.3% respectively in compressive deformation, and 112 GPa, 1 780 MPa, 2 000 MPa and 1.9% respectively in tensile deformation. High resolution transmission electron microscope (HRTEM) and nano beam electron diffraction (NBED) studies indicate that the cast metallic bulk glassy Cu 60 Zr 30 Ti 10 alloy consists of nanocrystals with a size of 4 nm embedded in glassy matrix. The nanoparticle is identified as CuZr and has point space group symmetry of pm3m and its lattice parameter is a =0.3 262 nm . The nanocrystalline phase grew up to 10 nm upon annealing at 430 ℃ for 10 min and caused the alloy brittle.
