In this study, the degradation efficiencies of zero-valent iron （ZVI） powders with different structures and components wereevaluated for methyl orange （MO）. The results show that the structure is an essential fact...In this study, the degradation efficiencies of zero-valent iron （ZVI） powders with different structures and components wereevaluated for methyl orange （MO）. The results show that the structure is an essential factor that affects degradation, andadded non-metallic elements help optimize the structure. The amorphous and balled-milled crystalline Fe7oSiloB2o hascomparative degradation efficiencies to MO with tl/2 values of 6.9 and 7.0 min, respectively. Increasing the boron contentcan create a favorable structure and promote degradation. The ball-milled crystalline Fe70B30 and Fe43.64B56.36 powdershave relatively short tl/2 values of 5.2 and 3.3 rain, respectively. The excellent properties are mainly attributed to theirheterogeneous structure with boron-doped active sites in ZVI. Composition segregation in the nanoscale range in anamorphous FeSiB alloy and small boron particles in the microscale range embedded in large iron particles prepared by ball-milling, both constitute effective galvanic cells that promote iron electron loss and therefore decompose organic chemicals.These findings may provide a new, highly efficient, low-cost commercial method for azo dye wastewater treatment usingZVI.展开更多
The lap joints of Fe-based metallic glass ribbons were carried by resistance spot welding, and the microstructures of spot welds were investigated by X-ray diffraction and transmission electron microscopy. The results...The lap joints of Fe-based metallic glass ribbons were carried by resistance spot welding, and the microstructures of spot welds were investigated by X-ray diffraction and transmission electron microscopy. The results indicated that the perfect formations of joints without typical defects such as spatter were achieved with optimized parameters. Except for little nano-particle Fe2B, no other crystalline particle was detected by TEM, revealing that the most microstructure in spot weld remains amorphous. The maximum tensile-shearing force was 45.0 N with the optimized parameters of 1 kA weld current, 30 N electrode force and 0.02 ms weld time. The spot weld failed as pullout failure mode propagating along the interface of nugget zone. The study demonstrates that resistance spot welding is an effective and practical welding process for Fe-based metallic glass.展开更多
Crystallization kinetics and phase transformation of bulk Fe64Co7Zr6Nd3B20 metallic glass were studied by X-ray diffractometry （XRD）, differential scanning calorimetry （DSC） and transmission electron microscopy （...Crystallization kinetics and phase transformation of bulk Fe64Co7Zr6Nd3B20 metallic glass were studied by X-ray diffractometry （XRD）, differential scanning calorimetry （DSC） and transmission electron microscopy （TEM）. Based on the Kissinger analyses, the activation energies for the nucleation and growth during the first, second and third crystallization-stages of the metallic glass are determined to be 294, 475 and 365 kJ/mol, respectively, and the activation energy for the glass transition is determined to be 1 242 kJ/mol. The Johnson-Mehl-Avrami （JMA） analysis under the isothermal condition reveals that the crystallization process is a three-dimensional controlled growth of nuclei at a constant nucleation rate. The crystalline grains are in the size of less than 50 nm after the selected annealing treatments. In the completely crystallized state, the alloy exhibits the maximum coercivity （Hc） of 34.8 kA/m and corresponding energy product of 11 kJ/m3.展开更多
Glass formation, mechanical and magnetic properties of the Fe76-xC7.0Si3.3B5.0P8.7Mox (x=0, 1 at.%, 3 at.% and 5 at.%) alloys prepared using an industrial Fe-P master alloy have been studied. With the substitution of ...Glass formation, mechanical and magnetic properties of the Fe76-xC7.0Si3.3B5.0P8.7Mox (x=0, 1 at.%, 3 at.% and 5 at.%) alloys prepared using an industrial Fe-P master alloy have been studied. With the substitution of Mo for Fe, glass-forming ability (GFA) was significantly enhanced and fully amorphous rods with a diameter of up to 5 mm were produced in the alloy with 3% Mo. The Mo-containing amorphous alloys also exhibited high fracture strength of 3635–3881 MPa and excellent magnetic properties including a high saturation magnetization of 1.10–1.41 T, a high Curie temperature and a low coercive force. The unique combination of high GFA, high fracture strength and excellent magnetic properties make the newly developed bulk metallic glasses viable for practical engineering applications.展开更多
The corrosion behavior of as-cast fully amorphous, structural relaxed amorphous and crystallized Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk metallic glasses (BMGs) in NaCl, HCl and NaOH solutions was investigated by electrochemica...The corrosion behavior of as-cast fully amorphous, structural relaxed amorphous and crystallized Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk metallic glasses (BMGs) in NaCl, HCl and NaOH solutions was investigated by electrochemical polarization and immersion methods. X-ray photoelectron spectroscopy measurements was used to analyze the changes of the elements on the alloy surface before and after immersion in various solutions. The corrosion resistance of the Fe65.5Cr4Mo4Ga4P12C5B5.5 BMG was better than its structural relaxation/crystallization counterparts and common alloys (such as stainless steel, carbonized steel, and steel) in the selected aqueous solutions. The high corrosion resistance of this alloy in corrosive solutions leads to the formation of Fe-, Cr- and Mo-enriched protective thin surface films.展开更多
基金supported by the Program of Introducing Innovative Research Team in Dongguan under Contract Number 2014607109Shenzhen Science and Technology Research Grants under Contract Numbers JCYJ20160422104921235,JCYJ20160422143659258 and JCYJ20160422144751573
文摘In this study, the degradation efficiencies of zero-valent iron （ZVI） powders with different structures and components wereevaluated for methyl orange （MO）. The results show that the structure is an essential factor that affects degradation, andadded non-metallic elements help optimize the structure. The amorphous and balled-milled crystalline Fe7oSiloB2o hascomparative degradation efficiencies to MO with tl/2 values of 6.9 and 7.0 min, respectively. Increasing the boron contentcan create a favorable structure and promote degradation. The ball-milled crystalline Fe70B30 and Fe43.64B56.36 powdershave relatively short tl/2 values of 5.2 and 3.3 rain, respectively. The excellent properties are mainly attributed to theirheterogeneous structure with boron-doped active sites in ZVI. Composition segregation in the nanoscale range in anamorphous FeSiB alloy and small boron particles in the microscale range embedded in large iron particles prepared by ball-milling, both constitute effective galvanic cells that promote iron electron loss and therefore decompose organic chemicals.These findings may provide a new, highly efficient, low-cost commercial method for azo dye wastewater treatment usingZVI.
基金the National Natural Science Foundation of China(No.51461031)the State Key Lab of Advanced Metals and Materials(No.2013-Z05)+2 种基金the Department of Education Fund of jiangxi(GJJ150733)the Beijing Natural Science Foundation(No.214200)the Program for Excellent Talents in Beijing Municipality
文摘The lap joints of Fe-based metallic glass ribbons were carried by resistance spot welding, and the microstructures of spot welds were investigated by X-ray diffraction and transmission electron microscopy. The results indicated that the perfect formations of joints without typical defects such as spatter were achieved with optimized parameters. Except for little nano-particle Fe2B, no other crystalline particle was detected by TEM, revealing that the most microstructure in spot weld remains amorphous. The maximum tensile-shearing force was 45.0 N with the optimized parameters of 1 kA weld current, 30 N electrode force and 0.02 ms weld time. The spot weld failed as pullout failure mode propagating along the interface of nugget zone. The study demonstrates that resistance spot welding is an effective and practical welding process for Fe-based metallic glass.
文摘Crystallization kinetics and phase transformation of bulk Fe64Co7Zr6Nd3B20 metallic glass were studied by X-ray diffractometry （XRD）, differential scanning calorimetry （DSC） and transmission electron microscopy （TEM）. Based on the Kissinger analyses, the activation energies for the nucleation and growth during the first, second and third crystallization-stages of the metallic glass are determined to be 294, 475 and 365 kJ/mol, respectively, and the activation energy for the glass transition is determined to be 1 242 kJ/mol. The Johnson-Mehl-Avrami （JMA） analysis under the isothermal condition reveals that the crystallization process is a three-dimensional controlled growth of nuclei at a constant nucleation rate. The crystalline grains are in the size of less than 50 nm after the selected annealing treatments. In the completely crystallized state, the alloy exhibits the maximum coercivity （Hc） of 34.8 kA/m and corresponding energy product of 11 kJ/m3.
基金supported by the National Natural Science Foundation of China (Grants Nos. 50725104 and 50841023)the National Basic Research Program of China (Grant No. 2007CB613903)China Post-doctoral Science Foundation (Grant No. 20080430019)
文摘Glass formation, mechanical and magnetic properties of the Fe76-xC7.0Si3.3B5.0P8.7Mox (x=0, 1 at.%, 3 at.% and 5 at.%) alloys prepared using an industrial Fe-P master alloy have been studied. With the substitution of Mo for Fe, glass-forming ability (GFA) was significantly enhanced and fully amorphous rods with a diameter of up to 5 mm were produced in the alloy with 3% Mo. The Mo-containing amorphous alloys also exhibited high fracture strength of 3635–3881 MPa and excellent magnetic properties including a high saturation magnetization of 1.10–1.41 T, a high Curie temperature and a low coercive force. The unique combination of high GFA, high fracture strength and excellent magnetic properties make the newly developed bulk metallic glasses viable for practical engineering applications.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50731005 and 50821001)SKPBRC (Grant Nos. 2010CB731604 and 2006CB605201)PCSIRT (Grant No. IRT0650)
文摘The corrosion behavior of as-cast fully amorphous, structural relaxed amorphous and crystallized Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk metallic glasses (BMGs) in NaCl, HCl and NaOH solutions was investigated by electrochemical polarization and immersion methods. X-ray photoelectron spectroscopy measurements was used to analyze the changes of the elements on the alloy surface before and after immersion in various solutions. The corrosion resistance of the Fe65.5Cr4Mo4Ga4P12C5B5.5 BMG was better than its structural relaxation/crystallization counterparts and common alloys (such as stainless steel, carbonized steel, and steel) in the selected aqueous solutions. The high corrosion resistance of this alloy in corrosive solutions leads to the formation of Fe-, Cr- and Mo-enriched protective thin surface films.
