• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.102-102
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• 2002

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.787-791
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• 1999

TiB$_2$powders were prepared by mechanical alloying, and the effect of Zr and Ta substitution for Ti was investigated. It was possible to produce titanium diboride phase by mechanical alloying titanium and boron elemental powders for 280 hours. The amorphization reaction, a common process which occurs during mechanical alloying, has not been found. When zirconium of which atomic radius was larger than that of titanium was substituted for Ti, the alloying time was greatly reduced. On the contrary, substitution of tantalum for titanium prolonged the alloying time because of the less negative heat of formation of tantalum diboride than that of titanium diboride.

• Journal of Korea Foundry Society
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• v.27 no.4
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• pp.159-166
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• 2007

Effects of alloying elements on the mechanical properties of 3.60wt%C-2.50wt%Si ductile cast iron with annealing and normalizing were investigated. Yield and tensile strengths were increased from 278 and 415 MPa to 316 and 440 MPa respectively as manganese content was increased upto 0.45wt% while elongation was decreased from 24.2 to 5.0%. The formers were increased and the latter was decreased with the increased amount of copper, molybdenum or nickel added. Meanwhile the tensile strength of annealed specimen was increased with the amount of alloying elements added, it was decreased by annealing. It was increased greatly by normalizing and the amount of alloying elements added except molybdenum.

• Journal of Powder Materials
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• v.18 no.6
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• pp.496-501
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• 2011

In this study, the effect of milling time on the microstructure and phase transformation behaviors of Ni-12 wt.%B powders was investigated using vibratory ball milling process. X-ray diffraction patterns showed that the phase transformation of mixed Ni-B elemental powder occurred after 50 hours of milling, with a formation of nickel boride phases. Through the study of microstructures in mechanical alloying process, it was considered that ball milling strongly accelerates solid-state diffusions of the Ni and B atoms during mechanical alloying process. The results of X-ray photoelectron spectroscopy showed that most of B atoms in the powder were linked to Ni with a formation of nickel boride phases after 200 hours of milling. It was finally concluded that mechanical alloying using ball milling process is feasible to synthesize fine and uniform nickel boride powders.

• Journal of Powder Materials
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• v.12 no.3
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• pp.179-185
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• 2005

As the electrodes of secondary battery are made with sulfur compounds, excellent electrode system of environmental non-toxicity, high specific energy density and low material cost can be obtained. In this study, the $FeS_2$ fine compound powders for active material in the battery were synthesized by mechanical alloying. Fine Fe-53.5 wt.%S powders of 450 nm of mean size were fabricated by mechanical alloying for 60 hours at the horizontal attritor. As the mechanical alloying time increases, particle size of Fe-53.5 wt.%S was decreased and steady state of Fe-53.5 wt.%S compound powders was obtained at 30 hours. Fe-53.5 wt.%S cathode shows the excellent discharge capacity (1011 mAh/g).

• Journal of Powder Materials
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• v.12 no.1
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• pp.70-78
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• 2005

Mechanical alloying using high-energy ball mill and subsequent spark plasma sintering (SPS) process was applied to understand mechanical alloying processing of Al-Fe alloy system. The thermal stability of mechanically alloyed Al-Fe alloy was intended to be enhanced by SPS process. Various analytical techniques including particle size analysis, density measurement, micro-Vickers hardness test, SEM, TEM, and X-ray diffractometry were adopted to find optimum processing conditions for mechanical alloying and subsequent SPS and to estimate thermal stability of the prepared alloy. It was found from the treatment of mechanically alloyed Al-8wt.%Fe powder mixture that needle-shaped $Al_3Fe$ precipitates was formed in the Al-Fe matrix, and the alloy compact showed enhanced densification and reached its full density with little loss of its fine microstructure. After heat treatment at $500^{\circC}$, it was also shown that the thermal stability of Al-8wt.%Fe alloy fabricated in the present study was enhanced, which was due to its fine microstructure developed by fast densification of SPS.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.372-378
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• 2005

Ni/YSZ ($Y_2O_3$-stabilized $ZrO_2$) composite powder for a cathode material in high temperature electrolysis(HTE) was synthesized by a mechanical alloying method with Ni and YSZ powder. Microstructure of the composite and cell thickness for HTE reaction has been analyzed with various techniques of XRD, SEM to investigate effects of fabrication conditions. Employing the composite material, furthermore, the unit cell for HTE has been studied to evolve hydrogen from water. XRD patterns showed that the composites after wet mechanical alloying were composed of respective nano-sized crystalline Ni and YSZ. While ethanol as additive for mechanical alloying increased to $20\;{\mu}m$ of average particle size of the composites, alpha-terpineol effectively decreased to sub-micro size of that. This study has been found out the evolution of hydrogen by HTE reaction employing the fabricated cathode material, showing 1.4 ml/min of $H_2$ generation rate as increasing $20\;{\mu}m$ of cathode thickness.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.90-91
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• 2002

영구자석 재료용 Sr-ferrite의 제조에 mechanical alloying (기계적 합금화)기술을 적용해서 초미세 결정립으로 구성된 고보자력의 Sr-ferrite를 제조해서 높은 보자력을 실현할 수 있는 것으로 보고하고 있다[1]. 그러나 이 새로운 방법으로 제조한 Sr-ferrite는 높은 보자력을 갖기는 하지만, 대단히 미세한 결정립들이 결합하여 입자를 구성하고 있어 자장을 가해서 입자를 배향시키기가 어렵다. 따라서 이 재료는 등방성 분말로 밖에 이용할 수 없는 결정적인 문제점이 있다. (중략)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.95.1-95.1
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• 2017

In this study, it has been tried to make the single Mo-Cu alloying targets with the Cu showing the best surface hardness that was determined by investigation on the coatings with the double target process. The single alloying targets were prepared by powder metallurgy methods such as mechanical alloying and spark plasma sintering. The nanocomposite coatings were prepared by reactive magnetron sputtering process with the single alloying targets in $Ar+N_2$ atmosphere. The microstructure changes of the Mo-Cu-N coatings with diverse Cu contents were investigated by using XRD, SEM and EDS. The mechanical properties of the coatings were evaluated by using nano-indentor, scratch test, and ball on disc methods. Especially, the coated samples were tested by using various lubricating oil to compare the property of anti wear-resistance. In this study, the nano-composite MoN-Cu coatings prepared using an alloying target was eventually compared with the coatings from the multiple targets.

• Korean Journal of Materials Research
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• v.14 no.8
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• pp.535-541
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• 2004

Thermoelectric $Zn_{4}Sb_3$ alloy powders were synthesized from elemental powders by mechanical alloying process and consolidated by hot pressing under controlled atmosphere. Single phase $Zn_{4}Sb_3$ was not obtained using a nominal stoichiometric composition, but near single phase $Zn_{4}Sb_3$ with remnant elemental Zn having a relatively high density was produced using a nominally 11.7 $at.\%$ Zn rich powders. Phase transformations during mechanical alloying were systematically investigated using XRD and SEM. Thermoelectric and transport properties were evaluated for the hot pressed specimens and compared with results of analogous studies.