• 전기화학회지
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• 제20권4호
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• pp.61-66
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• 2017

The cycle performance of Ti-Si alloy anode material for Li-ion batteries has been investigated as a function of loading level of electrode using a nodule type of substrate, in which the current collector of flat foil is also used for comparison. The Ti-Si alloy powders are prepared by mechanical alloying method. The electrodes with the nodule type of current collector exhibit enhanced cycling performance compared to those using the flat foil because the alloy particles are more strongly adhered to substrate and the stress caused by lithiation and delithiation reaction can be effectively relaxed by nodule-type morphology. It appears, however, that the cycle performance is critically dependent on the loading level of electrode, even when the nodule type of current collector is applied. With high loading level, cracks are initiated at surface of electrode due to a steep stress gradient through the electrode thickness during cycling, leading to capacity fading.

• 한국분말재료학회지
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• 제17권2호
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• pp.113-122
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• 2010

Two kinds of oxide-dispersion-strengthened (ODS) 316L stainless steel were manufactured using a wet mixing process(wet) and a mechanical alloying method (MA). An MA 316L ODS was prepared by a mixing of metal powder and a mechanical alloying process. A wet 316L ODS was manufactured by a wet mixing with 316L stainless steel powder. A solution of yttrium nitrate was dried after being in the wet 316L ODS alloy. The results showed that carbon and oxygen were effectively reduced during the degassing process before the hydroisostatic process (HIP) in both alloys. It appeared that the effect of HIP treatment on increase in impact energy was pronounced in the MA 316L ODS alloy. The MA 316L ODS alloy showed a higher yield strength and a smaller elongation, when compared to the wet 316L ODS alloy. This seemed to be attributed to the enhancement of bonding between oxide and matrix particles from HIP and to the presence of a finer oxide of about 20 nm from the MA process in the MA 316L ODS alloy.

• 한국분말재료학회지
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• 제14권2호
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• pp.97-100
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• 2007

The magnetic alloys of Cu-Fe ($Cu_{50}Fe_{50},\;Cu_{80}Fe_{20}\;and\;Cu_{90}Fe_{10}$) were prepared by a mechanical alloying method and their structural and magnetic behaviors were examined by X-ray diffraction and Mossbauer spectra. The magnetization curves did not distinctly show the saturation at 70 kOe for the concentrated alloys of $Cu_{80}Fe_{20}\;and\;Cu_{90}Fe_{10}$. The Mossbauer spectrum of $Cu_{80}Fe_{20}$ at room temperature shows one Lorentzian line of the paramagnetic phase, whereas the Mossbauer spectrum of $Cu_{90}Fe_{10}$ consists of sextet Lorentzian line at room temperature and a centered doublet line. The Mossbauer spectra of $Cu_{90}Fe_{10}$ measured in the temperature ranges from 13 to 295 K, implies that $Cu_{90}Fe_{10}$ to consists of two magnetic phases. One superimposed sextet corresponds to the ferromagnetic iron in Cu and the other one indicates the superparamagnetic iron rich phase.

• 한국주조공학회지
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• 제11권6호
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• pp.455-462
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• 1991

The formation of brittle intermetallic compound such as $VAl_3$ tends tp lower the toughness of V-Al alloys. Also, due to the high melting point of vanadium, it is difficult to make that alloy by previous ingot metallurgy method. To depress the technique has been adopted. The effect of particle size and milling time on the phase has been thoroughly studied. For mechanical alloying, SPEX mixed/mill has been used. The milling time and the composition of V and Al are varied to find the optimum condition of forming amorphous phase. The X-Ray Diffrection pattern, microstructure detection, microhandess test, experiments are carried out to analyze MA product. When the final step is reached, no lamellar-structure is detected. The steady state condition is observed after 8 hours and 10 hours milling for 15wt.%Al and 30wt.%Al alloy, respectively. The microhardness continuously increases up to 10 hours after then it remains constant.

• 한국분말재료학회지
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• 제7권3호
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• pp.143-148
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• 2000

NiAl alloy powders were prepared by mechanical alloying method and bulk specimens were produced using hot isostatic pressing techniques. This study focused on the transformation behavior and properties of Ni-Al mechanically alloyed powders and bulk alloys. Transformation behavior was investigated by differential scanning calorimeter (DSC), XRD and TEM. Particle size distribution and microstructures of mechanically alloyed powders were studied by particle size analyzer and scanning electron microscope (SEM). After 10 hours milling, XRB peak broadening appeared at the alloyed powders with compositions of Ni-36at%Al to 40at%Al. The NiAl and $Ni_3Al$ intermetallic compounds were formed after water quenching of solution treated powders and bulk samples at $1200^{\circ}C$, but the martensite phase was observed after liquid nitrogen quenching of solution treated powders. However, the formation of $Ni_3Al$ intermetallic compounds were not restricted by fast quenching into liquid nitrogen. It is considered to be caused by fast diffusion of atoms for the formation of stable $\beta$(NiAl) phase and $Ni_3Al$ due to nano sized grains during quenching. Amounts of martensite phase increased as the composition of aluminium component decreased in the Ni-Al alloy, which resulted in the increasing damping properties.

• 한국분말재료학회지
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• 제26권2호
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• pp.107-111
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• 2019

The activation energy to create a phase transformation or for the reaction to move to the next stage in the milling process can be calculated from the slop of the DSC plot, obtained at the various heating rates for mechanically activated Al-Ni alloy systems by using Kissinger's equation. The mechanically activated material has been called "the driven material" as it creates new phases or intermetallic compounds of AlNi in Al-Ni alloy systems. The reaction time for phase transformation by milling can be calculated using the activation energy obtained from the above mentioned method and from the real required energy. The real required energy (activation energy) could be calculated by subtracting the loss energy from the total input energy (calculated input energy from electric motor). The loss energy and real required energy divided by the reaction time are considered the "metabolic energy" and "the effective input energy", respectively. The milling time for phase transformation at other Al-Co alloy systems from the calculated data of Al-Ni systems can be predicted accordingly.

• Advances in materials Research
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• 제13권1호
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• pp.55-62
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• 2024

Cu-based sulfides have recently emerged as promising thermoelectric (TE) materials due to their low cost, non-toxicity, and abundance. In this research, point defect structure of Cu_2-xZnSnS₄ (x=0.1, 0.2, 0.3) samples were synthesized by the mechanical alloying method. Mixed powders of Cu, Zn, Sn and S were milled using high energy ball milling at a rotation speed of 300 rpm in Ar atmosphere. The milled Cu_2-xZnSnS₄ powders were heat-treated at 723 K for 24 h, and subsequently consolidated using spark plasma sintering (SPS) under an applied pressure of 60 MPa for 15 min. The thermal conductivity of the sintered Cu_2-xZnSnS₄ samples was evaluated. A well-defined Cu_2-xZnSnS₄ powders were successfully formed after milling for 16 h, with the particle sizes mostly distributed in the range of 60-100 nm. The lattice constants of aand cdecreased with increasing composition value x. The thermal conductivity of sintered x=0.1 sample exhibited the lowest value and attained 0.93 W/m K at 673 K.

• 열처리공학회지
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• 제8권3호
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• pp.222-228
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• 1995

Mechanical alloying behaviour was investigated after adding 6, 8, 12wt% Fe powder into A1 matrix, respectively, in order to develop Al alloy. And the mechanical characteristics of the alloy which was produced by the above method were studied. The hardness and ultimata tensile strength of the material with different compositions were found to be increased with annealing temperatures and holding times. Intermetallic compound of $Al_3Fe$ and carbide of $Al_4C_3$ phases, which were generated from the different compositions during annealing, were found. It was suggested that enhancement of mechanical properties of Al-Fe alloy system was due to the presence of these preapitates that constrained grain growth and blocked dislocation movement in the alloy system.

• 한국분말재료학회지
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• 제13권6호
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• pp.408-414
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• 2006

[ $MoSi_2$ ] alloys with Al, B or Nb were prepared by an advanced consolidation process that combined mechanical alloying with pulse discharge sintering (complex forming) to improve the mechanical properties. Their microstructure and mechanical properties were investigated. The $MoSi_2$ alloys fabricated by complex forming method showed very fine microstructure when compared with the sample sintered from commercial $MoSi_2$ powders. Alloys made from powders milled in Ar gas had fewer silica or alumina phases as compared to their counterparts sintered from powders milled in air. In densification of the sintered body, addition of B was more effective than Al or Nb. Both Victors hardness and tensile test indicated that the alloy fabricated by the complex forming method showed better properties than the sample sintered from commercial $MoSi_2$ powders. The Al added alloy sintered from the powders milled in air had the superior mechanical properties due to the suppression of $SiO_2$ and formation of fine $Al_2O_3$ particles.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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• pp.64-64
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• 2003