Ni layers were deposited on the two sides of pure Fe substrate by using electroplating to form Ni/Fe/Ni diffusion couple. After diffusion heat treatment, Fe–Ni laminated composite was obtained with Fe–Ni alloy/Fe/Fe...Ni layers were deposited on the two sides of pure Fe substrate by using electroplating to form Ni/Fe/Ni diffusion couple. After diffusion heat treatment, Fe–Ni laminated composite was obtained with Fe–Ni alloy/Fe/Fe–Ni alloy structure. The results indicate that the Fe–Ni layers combine well with the substrate and the Fe–Ni/Fe interface presents an interlocking microstructure with small-size grains. The concentration of element Ni in the Fe–Ni layer decreases from surface to interior exhibiting a gradient distribution. Geomagnetic shielding factor(SF) of Fe–Ni laminated composite can reach as high as 22.6, which is about seven times of that of pure Fe substrate. Mathematical equation of SF for laminated structure was derived according to magnetic circuit and resistance theory. The theoretical expression reveals that parameters such as the thickness and magnetic permeability of the shield material play an important role in the magnetic shielding behavior and the theoretical calculation results of SF coincide well with our experimental values.展开更多
<正>Fe—Ni alloy,as a widely applied ferromagnetic material,is synthesized using selective laser melting(SLM).The chemical compositions and microstructure of the SLM Fe—Ni alloy are characterized by X-ray diffr...<正>Fe—Ni alloy,as a widely applied ferromagnetic material,is synthesized using selective laser melting(SLM).The chemical compositions and microstructure of the SLM Fe—Ni alloy are characterized by X-ray diffraction(XRD), energy dispersive X-ray spectroscopy and scanning electron microscopy.It was found that the samples exhibited fine grains with homogenous distribution when a low laser scanning velocity was used.Moreover,the magnetic properties of the samples with different laser parameters are also measured.It shows that the SLM Fe—30%Ni alloy possesses a low coercivity and high saturation magnetization.It also can be obtained that SLM is an alternative faster method to prepare soft magnetic material with complex shapes.Moreover,the magnetic properties can be influenced by the laser parameters.展开更多
<正>Effect of multiple direct and reverse martensitic transformations on fragmentation of austenitic grains in Fe-Ni alloys have been studied by X-ray diffraction and scanning electron microscopy.An ultra-fine s...<正>Effect of multiple direct and reverse martensitic transformations on fragmentation of austenitic grains in Fe-Ni alloys have been studied by X-ray diffraction and scanning electron microscopy.An ultra-fine structure was formed by fragmentation inside austenitic grains due to progressing misorientation of austenitic sub-grains during multipleγ-α-γ-martensitic phase transitions.An increase in the number ofγ-α-γ-transformations increases misorientation angle between austenitic sub-grains and leads to transformation of an austenitic single crystal into a textured polycrystal.It has been shown that multipleγ-α-γ-martensitic phase transitions change the mechanism of internal stress relaxation from dislocation-based to deformation twinning.展开更多
基金Projects(51304091,U1302274)supported by the National Natural Science Foundation of ChinaProjects(2013FD009,2013FZ007)supported by Applied Basic Research Program of Yunnan Province,ChinaProject(2012HB009)supported by the Candidate Talents Training Fund of Yunnan Province,China
文摘Ni layers were deposited on the two sides of pure Fe substrate by using electroplating to form Ni/Fe/Ni diffusion couple. After diffusion heat treatment, Fe–Ni laminated composite was obtained with Fe–Ni alloy/Fe/Fe–Ni alloy structure. The results indicate that the Fe–Ni layers combine well with the substrate and the Fe–Ni/Fe interface presents an interlocking microstructure with small-size grains. The concentration of element Ni in the Fe–Ni layer decreases from surface to interior exhibiting a gradient distribution. Geomagnetic shielding factor(SF) of Fe–Ni laminated composite can reach as high as 22.6, which is about seven times of that of pure Fe substrate. Mathematical equation of SF for laminated structure was derived according to magnetic circuit and resistance theory. The theoretical expression reveals that parameters such as the thickness and magnetic permeability of the shield material play an important role in the magnetic shielding behavior and the theoretical calculation results of SF coincide well with our experimental values.
基金Acknowledgment Authors thank Mr. Eric AUBRY (Nipson Belfort France), for his assistance concerning magnetic measurements.
文摘<正>Fe—Ni alloy,as a widely applied ferromagnetic material,is synthesized using selective laser melting(SLM).The chemical compositions and microstructure of the SLM Fe—Ni alloy are characterized by X-ray diffraction(XRD), energy dispersive X-ray spectroscopy and scanning electron microscopy.It was found that the samples exhibited fine grains with homogenous distribution when a low laser scanning velocity was used.Moreover,the magnetic properties of the samples with different laser parameters are also measured.It shows that the SLM Fe—30%Ni alloy possesses a low coercivity and high saturation magnetization.It also can be obtained that SLM is an alternative faster method to prepare soft magnetic material with complex shapes.Moreover,the magnetic properties can be influenced by the laser parameters.
基金This work was supported by research grant UFFD-RFFD- 2009.
文摘<正>Effect of multiple direct and reverse martensitic transformations on fragmentation of austenitic grains in Fe-Ni alloys have been studied by X-ray diffraction and scanning electron microscopy.An ultra-fine structure was formed by fragmentation inside austenitic grains due to progressing misorientation of austenitic sub-grains during multipleγ-α-γ-martensitic phase transitions.An increase in the number ofγ-α-γ-transformations increases misorientation angle between austenitic sub-grains and leads to transformation of an austenitic single crystal into a textured polycrystal.It has been shown that multipleγ-α-γ-martensitic phase transitions change the mechanism of internal stress relaxation from dislocation-based to deformation twinning.
基金This work was supported by the Financial support from the NSF of China (21066007) the NSF of Tianjin China (10JCZDJC23800) and the NSF of Mongolia China (2009BS0203).
基金supported by the National Natural Science Foundation of China under Grant No.50871069 “Chen Guang”project under Grant No.09CG51 sponsored by Shanghai Municipal Education Commission and Shanghai Education Development Foundation