Magnetic and mössbauer studies on ductile Fe-Cr-Co permanent magnet alloys

Iron-chromium-cobalt alloys possess attractive magnetic properties combined with good formability and hence are identified as technologically important magnetic materials. Alloys with compositions Fe-28·9 Cr-15·6 Co and Fe-28·4 Cr-20·1Co (weight percent) have been studied. Heat-treatment parameters during thermomagnetic treatment viz temperature, time and external magnetic field were optimized with reference to magnetic properties. The fully treated anisotropic alloys develop remanence=11·5–12·0 kilo Gauss, coercivity=600–650 Oersted and energy product=4–4·5 million Gauss Oersted. Electron microscopic and Mössbauer spectroscopic techniques were used to identify the original and transformed phases. During the various stages of the development of the alloy, the changes in mechanical hardness were correlated with magnetic hardness.     

Influence of HDDR treatment on magnetic properties of TbFe2- and DyFe2-based intermetallics

Magnetic properties of TbFe₂, DyFe₂, Tb(Fe_0.8M_0.2)₂ and Dy(Fe_0.8M_0.2)₂ with M=Co, Al, Si, Ga alloys affected by the Hydrogenation-Decomposition-Desorption-Recombination processing have been studied. After hydrogen treatment the coercive force H_c grows sharply, so HDDR-powders can be used as isotropic permanent magnets with the energy product up to 26 MG Oe at T=77 K. In Dy(Fe_0.8Al_0.2)₂ at T<10 K the stepwise magnetic reversal has been observed. The HDDR-treatment increases the critical field of magnetic reversal from 11 up to 18.4 kOe at 4.2 K. It is shown that the effect of the stepwise magnetic reversal is caused by a heat release in a sample during an avalanche motion of narrow domain walls.     

独立分量分析理论在海底管道漏磁检测中的应用

应用独立分量分析(ICA)方法对海底管道缺陷漏磁法检测中电磁干扰的消除进行了研究，阐述了漏磁检测和负熵法ICA快速算法的原理，应用相应的分析工具研究了试验数据。结果表明，在试验室条件下该方法能很好地分离出缺陷信号和电磁干扰信号。     

Structure, hyperfine interactions and magnetization studies of mechanically alloyed Fe50Ge50 and Fe62Ge38

X-ray diffraction, Mössbauer spectroscopy and magnetization measurements were used to study the structure and some magnetic properties of Fe₅₀Ge₅₀ and Fe₆₂Ge₃₈ prepared by mechanical alloying from the elemental powders. In both cases in the early stages of milling the intermediate paramagnetic FeGe₂ phase was formed. The mechanical alloying process of Fe₅₀Ge₅₀ resulted in the formation of the paramagnetic FeGe (B20) phase with an average crystallite size of about 15 nm. In the case of the Fe₆₂Ge₃₈, the ferromagnetic Fe₅Ge₃ (β) phase with a Curie temperature of about 430 K was obtained. The average crystallite size was about 9 nm. The average hyperfine magnetic field of about 16 T allowed it to determine that more than four germanium atoms exist in the nearest environment of the ⁵⁷Fe isotopes in the Fe₅Ge₃ phase.     

Electron Microscopy Imaging Applications of Room Temperature Ionic Liquids in the Biological Field: A Review

For biological imaging using electron microscopy (EM), the use of room-temperature ionic liquids (RTILs) has been proposed as an alternative to traditional lengthy preparation methods. With their low vapor pressures and conductivity, RTILs can be applied onto hard-to-image soft and/or wet samples without dehydration – allowing for a more representative, hydrated state of material and opening the possibility for visualization of in situ physiological processes using conventional EM systems. However, RTILs have yet to be utilized to their full potential by microscopists and microbiologists alike. To this end, this review aims to provide a comprehensive summary of biological applications of RTILs for EM to bridge the RTIL, in situ microscopy, and biological communities. We outline future research avenues for the use of RTILs for the EM observation of biological samples, notably i) RTIL selection and optimization, ii) applications for live cell processes and iii) electron beam and ionic liquid interaction studies.     

化学镀钴-磷基多元合金的研究现状

由于钴－磷基合金膜具有优异的磁性能和较高的耐蚀性，能有效的用于数字存储装置，已引起人们的极大关注。     

Characterization of angular dependence of macroscopic magnetic properties in ASTM 36 steel using magnetic Barkhausen noise

Angular-dependent magnetic Barkhausen noise measurements were performed on ASTM 36 steel samples for various values of applied uniaxial stress. The maximum differential permeability and the coercive field are obtained from this Barkhausen signals. The angular dependence of these macroscopic magnetic properties is studied. The tension for which the magneto-elastic energy balances the anisotropic energy is estimated. The results are discussed based on the domain wall theory.     

Evaluation of tempering induced changes in the hardness profile of case-carburised EN36 steel using magnetic Barkhausen noise analysis

The effect of tempering on the magnetic Barkhausen noise (MBN) signal profile was studied in case-carburised EN36 steel using a range of magnetic excitation frequencies and a number of frequency ranges for analysis of the MBN signal. The MBN level generally increases with tempering due to coarsening of the microstructure. With higher values of excitation frequency, f_EX, the MBN profile exhibits a single peak, but with low values of f_EX, double peaks are observed. The MBN peak obtained with higher f_EX was found to correlate well with hardness changes in a region, down to 100 μm below the surface. The analysis of the MBN signal produced with low f_EX, in narrow frequency ranges selected by software frequency filtering, showed variations in the extent of changes in the relative height of the two MBN peaks in the profile. After taking into account the skin depth-frequency relation for the MBN signal, variations in the values of the two MBN peaks in different analysing frequency ranges were found to correlate well with hardness variations at different depths down to 425 μm below the surface. An empirical relationship has been established between the hardness-depth profile and the MBN measurements.     

关于磁粉探伤标准中电磁轭提升力涵义的讨论

对磁粉探伤标准中所表述的电磁轭提升力涵义有两种不同的理解，一为提升力仅是对设备的要求，而与灵敏度无关；二为提升力与灵敏度紧密相关。对该两种理解进行分析讨论，认为第二种理解更合乎其原意。     

Effect of a direct magnetic field on the interfacial microstructure between molten aluminium and solid iron

Many processing techniques, such as hot dip aluminizing, bimetal formation, liquid metal corrosion, cementing, welding and diffusion bonding, are basically dependent on interfacial reactions [1-3]. It is therefore important to investigate the formation and growth of intermetallic layers at the interface. There have been several studies carried out to examine chemical compositions and growth kinetics of intermetallic layers in the Al-Fe system [4-9]. Most authors have come to an agreement that…