The microstructure,microhardness,and corrosion resistance of laser cladding Ni−WC coating on the surface of AlSi5Cu1Mg alloy were investigated by scanning electron microscopy,X-ray diffraction,microhardness testing,im...The microstructure,microhardness,and corrosion resistance of laser cladding Ni−WC coating on the surface of AlSi5Cu1Mg alloy were investigated by scanning electron microscopy,X-ray diffraction,microhardness testing,immersion corrosion testing,and electrochemical measurement.The results show that a smooth coating containing NiAl,Ni_(3)Al,M_(7)C_(3),M_(23)C_(6)phases(M=Ni,Al,Cr,W,Fe)and WC particles is prepared by laser cladding.Under a laser scanning speed of 120 mm/min,the microhardness of the cladding coating is 9−11 times that of AlSi5Cu1Mg,due to the synergistic effect of excellent metallurgical bond and newly formed carbides.The Ni−WC coating shows higher corrosion potential(−318.09 mV)and lower corrosion current density(12.33μA/cm^(2))compared with the matrix.The crack-free,dense cladding coating obviously inhibits the penetration of Cl^(−)and H^(+),leading to the remarkedly improved corrosion resistance of cladding coating.展开更多
Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magn...Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magnetic field intensity had a remarkable influence on the shape of μ-T curves. For amorphous alloy, the sharp Hopkinson peak of μ-T curve disappeared gradually with the increase of magnetic field intensity.展开更多
Feo.eCoo.^seHfTBsCu! nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution ...Feo.eCoo.^seHfTBsCu! nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution for Fe can enhance the curie temperature of amorphous alloy (Tc = 630 °C) and improve the magnetization of nanocrystalline alloy at high temperature ( = 1.56T at 550 °C). After annealing amorphous precursor at 550 °C for 1 hour, the optimum nanocrystalline alloy can be obtained which shows the local minimum coercivity ( = 16 A/m). The coercivity increases with the increase of annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization. Furthermore, additions of Hf and B elements reduce the melting temperature of the alloy studied comparing with the Fe-Co binary alloy.展开更多
The microstructures and corrosion behavior of AlSi5 CulMg alloy modified with different contents of La were investigated.Optical microscopy observations showed that the microstructures of AlSi5 Cu1 Mg-xLa(x = 0, 0.3, ...The microstructures and corrosion behavior of AlSi5 CulMg alloy modified with different contents of La were investigated.Optical microscopy observations showed that the microstructures of AlSi5 Cu1 Mg-xLa(x = 0, 0.3, 0.6, and 0.9 wt%) alloy transformed from coarse cellular to fine cellular as the content of La increased from 0 to 0.9 wt%. The results of electrochemical measurement and immersion test in 3.5 wt% NaCl solution showed that the corrosion resistance of AlSi5 CulMg-xLa alloy strongly depended on its microstructures. The AlSi5 Cu1 Mg-0.6 La sample exhibited the highest corrosion resistance due to its fine cellular structure and the cathode phases coated by the La element. The covering film of La hindered the corrosion electron flowing between the cathode and the anode. As a result, the corrosion current density of the AlSi5 CulMg-0.6 La alloy was only about 40% that of the matrix alloy in the electrochemical measurement.展开更多
文摘The microstructure,microhardness,and corrosion resistance of laser cladding Ni−WC coating on the surface of AlSi5Cu1Mg alloy were investigated by scanning electron microscopy,X-ray diffraction,microhardness testing,immersion corrosion testing,and electrochemical measurement.The results show that a smooth coating containing NiAl,Ni_(3)Al,M_(7)C_(3),M_(23)C_(6)phases(M=Ni,Al,Cr,W,Fe)and WC particles is prepared by laser cladding.Under a laser scanning speed of 120 mm/min,the microhardness of the cladding coating is 9−11 times that of AlSi5Cu1Mg,due to the synergistic effect of excellent metallurgical bond and newly formed carbides.The Ni−WC coating shows higher corrosion potential(−318.09 mV)and lower corrosion current density(12.33μA/cm^(2))compared with the matrix.The crack-free,dense cladding coating obviously inhibits the penetration of Cl^(−)and H^(+),leading to the remarkedly improved corrosion resistance of cladding coating.
基金This work was supported by the National Natural Science Foundation of China(No.59871013).
文摘Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magnetic field intensity had a remarkable influence on the shape of μ-T curves. For amorphous alloy, the sharp Hopkinson peak of μ-T curve disappeared gradually with the increase of magnetic field intensity.
基金supported by the 5^(th)framework Program of European Community,research project“Soft Magnetic.Nanomaterials for High Temperature and High Frequency Functional Application in Power Electronics",contract No.GSRD-CT-2001-03009.the key project of National Natural Science Foundation of China(50235030).
文摘Feo.eCoo.^seHfTBsCu! nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution for Fe can enhance the curie temperature of amorphous alloy (Tc = 630 °C) and improve the magnetization of nanocrystalline alloy at high temperature ( = 1.56T at 550 °C). After annealing amorphous precursor at 550 °C for 1 hour, the optimum nanocrystalline alloy can be obtained which shows the local minimum coercivity ( = 16 A/m). The coercivity increases with the increase of annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization. Furthermore, additions of Hf and B elements reduce the melting temperature of the alloy studied comparing with the Fe-Co binary alloy.
基金supported financially by the National Natural Science Foundation of China (No. 51364035)the Natural Science Foundation of Jiangxi Province (No. 20171BAB206034)
文摘The microstructures and corrosion behavior of AlSi5 CulMg alloy modified with different contents of La were investigated.Optical microscopy observations showed that the microstructures of AlSi5 Cu1 Mg-xLa(x = 0, 0.3, 0.6, and 0.9 wt%) alloy transformed from coarse cellular to fine cellular as the content of La increased from 0 to 0.9 wt%. The results of electrochemical measurement and immersion test in 3.5 wt% NaCl solution showed that the corrosion resistance of AlSi5 CulMg-xLa alloy strongly depended on its microstructures. The AlSi5 Cu1 Mg-0.6 La sample exhibited the highest corrosion resistance due to its fine cellular structure and the cathode phases coated by the La element. The covering film of La hindered the corrosion electron flowing between the cathode and the anode. As a result, the corrosion current density of the AlSi5 CulMg-0.6 La alloy was only about 40% that of the matrix alloy in the electrochemical measurement.
