• Investigative Magnetic Resonance Imaging
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• v.19 no.2
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• pp.76-87
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• 2015

Purpose: There is an ongoing search for a stent material that produces a reduced susceptibility artifact. This study evaluated the effect of manganese (Mn) content on the MRI susceptibility artifact of ferrous-manganese (Fe-Mn) alloys, and investigated the correlation between MRI findings and measurements of Fe-Mn microstructure on X-ray diffraction (XRD). Materials and Methods: Fe-Mn binary alloys were prepared with Mn contents varying from 10% to 35% by weight (i.e., 10%, 15%, 20%, 25%, 30%, and 35%; designated as Fe-10Mn, Fe-15Mn, Fe-20Mn, Fe-25Mn, Fe-30Mn, and Fe-35Mn, respectively), and their microstructure was evaluated using XRD. Three-dimensional spoiled gradient echo sequences of cylindrical specimens were obtained in parallel and perpendicular to the static magnetic field (B0). In addition, T1-weighted spin echo, T2-weighted fast spin echo, and $T2^*$weighted gradient echo images were obtained. The size of the low-intensity area on MRI was measured for each of the Fe-Mn binary alloys prepared. Results: Three phases of ${\alpha}^{\prime}$-martensite, ${\gamma}$-austenite, and ${\varepsilon}$-martensite were seen on XRD, and their composition changed from ${\alpha}^{\prime}$-martensite to ${\gamma}$-austenite and/or ${\varepsilon}$-martensite, with increasing Mn content. The Fe-10Mn and Fe-15Mn specimens comprised ${\alpha}^{\prime}$-martensite, the Fe-20Mn and Fe-25Mn specimens comprised ${\gamma}+{\varepsilon}$ phases, and the Fe-30Mn and Fe-35Mn specimens exhibited a single ${\gamma}$ phase. The size of the low-intensity areas of Fe-Mn on MRI decreased relative to its microstructure on XRD with increasing Mn content. Conclusion: Based on these findings, proper conditioning of the Mn content in Fe-Mn alloys will improve its visibility on MR angiography, and a Mn content of more than 25% is recommended to reduce the magnetic susceptibility artifacts on MRI. A reduced artifact of Fe-Mn alloys on MRI is closely related to the paramagnetic constitution of ${\gamma}$-austenite and/or ${\varepsilon}$-martensite.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.76-81
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• 2005

The effect of micro-pulse plasma nitriding temperature and time on the case thickness, hardness and nitride formation in the surface of Fe-12Cr-22Mn-X alloy with 3% Co and 1% Ti alloys elements investigated. External compound layer and internal diffusion layer was constituted in plasma nitride case of Fe-12Cr-22Mn-X alloys and formed nitride phase such as ${\gamma}'-Fe4N\;and\;{\varepsilon}-Fe2-3N$. Case depth increased with increasing the plasma nitriding temperature and time. Surface hardness of nitrided Fe-12Cr-22Mn-X alloys obtained the above value of Hv 1,600 and case depth obtained the above value of $45{\mu}m$ in Fe-12Cr-22Mn-3Co alloy and $60{\mu}m$ in Fe-12Cr-22Mn-1Ti alloy. Wear-resistance increased with increasing plasma nitriding time and showing the higher value in Fe-12Cr-22Mn-1Ti alloy than Fe-12Cr-22Mn-3Co alloy.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.70-75
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• 2005

The damping property of Fe-12Cr-22Mn-X alloys has been investigated to develop high damping and high strength alloy. Particularly, the effect of the phase of austenite, alpha and epsilon martensite, which constitute the structure of the alloys Fe-12Cr-22Mn-X alloys, on the damping capacity at room temperature has been investigated. Various fraction of these phases were formed depending on the alloy element and cold work degree. The damping capacity is strongly affected by ${\varepsilon}$ martensite while the other phase, such as ${\alpha}'$ martensite, actually exhibit little effect on damping capacity. In case of Fe-12Cr-22Mn-3Co alloy, the large volume fraction of ${\varepsilon}$ martensite formed at about 30% cold rolling, and in case of Fe-12Cr-22Mn-1Ti alloy, formed at about 20% cold rolling and showed the highest damping capacity. Damping capacity showed higher value in Fe-12Cr-22Mn-1Ti alloy than one in Fe-12Cr-22Mn-3Co alloy.

• Korean Journal of Materials Research
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• v.22 no.4
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• pp.169-173
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• 2012

Recently, various attempts to produce a heat sink made of Al 6xxx alloys have been carried out using die-casting. In order to apply die-casting, the Al alloys should be verified for die-soldering ability with die steel. It is generally well known that both Fe and Mn contents have effects on decreasing die soldering, especially with aluminum alloys containing substantial amounts of Si. However, die soldering has not been widely studied for the low Si aluminum (1.0~2.0wt%) alloys. Therefore, in this study, an investigation was performed to consider how the soldering phenomena were affected by Fe and Mn contents in low Si aluminum alloys. Each aluminum alloy was melted and held at $680^{\circ}C$. Then, STD61 substrate was dipped for 2 hr in the melt. The specimens, which were air cooled, were observed using a scanning electron microscope and were line analyzed by an electron probe micro analyzer. The SEM results of the dipping soldering test showed an Al-Fe inter-metallic layer in the microstructure. With increasing Fe content up to 0.35%, the Al-Fe inter-metallic layer became thicker. In Al-1.0%Si alloy, the additional content of Mn also increased the thickness of the inter-metallic layer compared to that in the alloy without Mn. In addition, EPMA analysis showed that Al-Fe inter-metallic compounds such as $Al_2Fe$, $Al_3Fe$, and $Al_5Fe_2$ formed in the die soldering layers.

• Applied Microscopy
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• v.21 no.2
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• pp.57-66
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• 1991

The main purpose of this paper was to investigate the change of rapidly solidified microstructures and dispersoid behavior according to heat-treatment in the Al-Fe-V-Si-(Mn) alloys. It was found that (111) preferred orientation identified by X-ray diffraction and fine subgrain/large grain were observed in the rapidly solidified Al-Fe-V-Si-(Mn) alloys. Cell boundary of the zone A was composed of the microcrystalline, whereas that of the zone B was amorphous. Decomposition of the Al-Fe-V-Si-(Mn) alloys occurred at about $300^{\circ}C$. These alloys exhibited excellent thermal stability at the elevated temperature. Microstructure of the zone B was more stable than that of the zone A. The spherical dispersoid and 5-fold symmetry phase was also more thermally stable than the amorphous structure of cell boundary.

• Journal of Korea Foundry Society
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• v.24 no.1
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• pp.45-51
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• 2004

Fe and Si are common impurity elements in the aluminum alloys. In this investigation, the effects of the addition of Fe and Si on the age-hardening behaviors of the Al-Cu-Mn-Ti-Zr-Cd casting alloys were examined through hardness measurements, calorimetric techniques and observation of the transmission electron microscopy. The addition of Fe depresses the formation of GPII and ${\theta}'$, and thus retards the peak aging time and reduces the peak hardness of the Al-Cu-Mn-Ti-Zr-Cd alloys. On the contrary, the addition of Si accelerates the formation of GPII and ${\theta}'$ and thus accelerates age-hardening behaviors of the Al-Cu-Mn-Ti-Zr-Cd alloys.

• Korean Journal of Materials Research
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• v.33 no.3
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• pp.95-100
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• 2023

This research examines the effect of adding aluminum on the structural, phasic, and magnetic properties of CoCrFe NiMnAl_x high-entropy alloys. To this aim, the arc-melt process was used under an argon atmosphere for preparing cast samples. The phasic, structural, and magnetic properties of the samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrational magnetometry (VSM) analyses. Based on the results, the addition of aluminum to the compound caused changes in the crystalline structure, from FCC solid solution in the CoCrFeNiMn sample to CoCrFeNiMnAl BBC solid solution. It was associated with changes in the magnetic property of CoCrFeNiMnAl_x high-entropy alloys, from paramagnetic to ferromagnetic. The maximum saturation magnetization for the CoCrFeNiMnAl casting sample was estimated to be around 79 emu/g. Despite the phase stability of the FCC solid solution with temperature, the solid solution phase formed in the CrCrFeNiMnAl high-entropy compound was not stable, and changed into FCC solid solution with temperature elevation, causing a reduction in saturation magnetization to about 7 emu/g.

• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.37-41
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• 1991

Amorphous $Fe_{68.5}Co_5M_3Cu_1Si_{13.5}B_9(M=Nb, Mo, Mn, Cr)$ alloys were prepared by using rapidly quenching techinque and were annealed above their crystallization temperatures. Coercive force, initial permeability and AC power loss of the annealed $Fe_{68.5}Co_5M_3Cu_1Si_{13.5}B_9(M=Nb, Mo, Mn, Cr)$ alloys have been studied systematically. Nanocrystallines are formed in the annealed alloys which include Mo and Nb. Remarkably improved soft magnetic properties are obtained in the alloys whose average grain size is around 10 nm. However, soft magnetic properties of the alloys are degraded when grain size is less than IOnm or larger than 15nm. It is considered that the degradation of soft magnetic properties in the alloys whose average grain size is less than 10 nm is due to the Fe-rich amorphous phase retained at grain boundary during the initial crystallization process.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.4
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• pp.243-251
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• 1996

Dilatometric experiment and thermodynamic calculation have been performed to determine $M_s$, $A_s$ and driving forces for ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation of Fe-Mn alloys. The transformation temperatures($M_s$, $A_s$, $T_o) were decreased with increasing manganese content and were newly formulated as a function of manganese content. Driving force for ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation was increased from -75J/mole to -105J/mole with increasing manganese content from 15wt.% to 25wt.%. Transformation temperature hysteresis($A_s-M_s$) was also increased from 50K to 80K with increasing mangenese content from 15wt.% to 25wt.%. The small driving force(-75J/mole~-105J/mole) and small ${\Delta}T$(50K~80K) for ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation indicated that Fe-Mn alloys behave like thermoelastic martensitic alloys : We would like to call them semi-thermoelastic martensitic alloys.

• Journal of Powder Materials
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• v.25 no.3
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• pp.208-212
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• 2018

In this paper, a new $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ high entropy alloy (HEA) is identified as a strong candidate for the single face-centered cubic (FCC) structure screened using the upgraded TCFE2000 thermodynamic CALPHAD database. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA is fabricated using the mechanical (MA) procedure and pressure-less sintering method. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA, which consists of elements with a large difference in melting point and atomic size, is successfully fabricated using powder metallurgy techniques. The MA behavior, microstructure, and mechanical properties of the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA are systematically studied to understand the MA behavior and develop advanced techniques for fabricating HEA products. After MA, a single FCC phase is found. After sintering at $900^{\circ}C$, the microstructure has an FCC single phase with an average grain size of $18{\mu}m$. Finally, the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA has a compressive yield strength of 302 MPa.