Determination of Intrinsic Magnetic Parameters of SmCo5 Phase in Sintered Samples

2005 ◽  
Vol 498-499 ◽  
pp. 129-133 ◽  
Author(s):  
Marcos Flavio de Campos ◽  
Fernando José Gomes Landgraf
Keyword(s):  
Powder Metallurgy ◽  
Domain Wall ◽  
Kerr Effect ◽  
Critical Diameter ◽  
Optical Microscope ◽  
Domain Theory ◽  
Magnetic Domains ◽  
Magnetic Parameters ◽  
Intrinsic Parameters

SmCo5 magnets are usually produced by powder metallurgy route, including milling, compaction and orientation under magnetic field, sintering and heat treatment. The samples produced by powder metallurgy, with grain size around 10 μm, are ideal for determination of intrinsic parameters. The first step for determination of intrinsic magnetic parameters is obtaining images of domain structure in demagnetized samples. In the present study, the domain images were produced by means of Kerr effect, in a optical microscope. After the test of several etchings, Nital appears as the most appropriate for observation of magnetic domains by Kerr effect. Applying Stereology and Domain Theory, several intrinsic parameters of SmCo5 phase were determined: domain wall energy 120 erg/cm2, critical diameter for single domain particle size 2 μm and domain wall thickness 60 Å. In the case of SmCo5, and also other phases with high magnetocrystalline anisotropy, Domain Theory presents several advantages when compared with Micromagnetics.

Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

2020 ◽  
Vol 17 (3) ◽  
pp. 8206-8213
Author(s):  
J. Alias
Keyword(s):  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Optical Microscope ◽  
High Reactivity ◽  
Aluminium Content ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

Microstructures and Properties of Ti-Nb Alloys Produced by Powder Metallurgy

2011 ◽  
Vol 80-81 ◽  
pp. 431-435 ◽  
Author(s):  
Zheng Cun Zhou ◽  
J. Du ◽  
H. Yang ◽  
S.Y. Gu ◽  
Y.J. Yan
Keyword(s):  
Powder Metallurgy ◽  
Testing Machine ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Sintered Alloy ◽  
Xrd Diffraction ◽  
Β Phase ◽  
Ω Phase ◽  
Nb Content ◽  
And Storage

Ti-Nb alloys were prepared by powder metallurgy. Their microstructures are detected by the XRD diffraction and are observed using an optical microscope. The mechanical properties are tested using a dynamic mechanical analysis (DMA) Q800 from TA Instruments in single cantilever mode and using a 100 KN MTS testing machine with control software. It has been found that the sintered Ti-Nb alloys possess the stable α and β phases and the amount in β phase increases with increasing Nb content. The water quenched Ti-35.4Nb alloy contains α,,and βM. The as-sintered alloy has higher yield stress and storage modulus than the water quenched Ti-35.4Nb alloy, which is resulted from the α phase with high modulus in the as-sintered alloy. The ω phase can be precipitated from βMwhen the water quenched Ti-35.4Nb alloy is aged at 300 °C, causing the modulus to increase since ω phase has large modulus.

A scanning reflection X-ray microscope for magnetic imaging in the EUV range

2019 ◽  
Vol 26 (6) ◽  
pp. 2040-2049
Author(s):  
Andreas Schümmer ◽  
H.-Ch. Mertins ◽  
Claus Michael Schneider ◽  
Roman Adam ◽  
Stefan Trellenkamp ◽  
...  
Keyword(s):  
Kerr Effect ◽  
Magnetic Circular Dichroism ◽  
Thin Foil ◽  
Light Sources ◽  
Magnetic Domains ◽  
X Ray ◽  
Magnetic Imaging ◽  
Magnetic Dichroism ◽  
Magneto Optical Kerr Effect ◽  
Microscope Design

The mechanical setup of a novel scanning reflection X-ray microscope is presented. It is based on zone plate optics optimized for reflection mode in the EUV spectral range. The microscope can operate at synchrotron radiation beamlines as well as at laboratory-based plasma light sources. In contrast to established X-ray transmission microscopes that use thin foil samples, the new microscope design presented here allows the investigation of any type of bulk materials. Importantly, this permits the investigation of magnetic materials by employing experimental techniques based on X-ray magnetic circular dichroism, X-ray linear magnetic dichroism or the transversal magneto-optical Kerr effect (T-MOKE). The reliable functionality of the new microscope design has been demonstrated by T-MOKE microscopy spectra of Fe/Cr-wedge/Fe trilayer samples. The spectra were recorded at various photon energies across the Fe 3p edge revealing the orientation of magnetic domains in the sample.

Depinning Field of Vortex Domain Wall in Wide Magnetic Wires with Asymmetric Notches Using Magneto-Optical Kerr Effect Microscopy

2019 ◽  
Vol 48 (3) ◽  
pp. 1363-1367 ◽  
Author(s):  
Deng-Shiang Shiu ◽  
Yun Hong ◽  
Chin-Han Su ◽  
Kao-Fan Lai ◽  
Jong-Ching Wu ◽  
...  
Keyword(s):  
Domain Wall ◽  
Kerr Effect ◽  
Optical Kerr Effect ◽  
Magneto Optical Kerr Effect ◽  
Magnetic Wires ◽  
Depinning Field
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