• 한국주조공학회지
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• 제43권6호
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• pp.286-293
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• 2023

본 연구에서는 고강도 Al-Mg-Zn계 알루미늄 합금 연속주조 빌렛의 균질화처리 과정 중 미세조직 전개과정을 다양한 장비(OM, SEM, EDS, DSC)로 분석 및 고찰하였다. 우선, 연속주조된 알루미늄 합금 빌렛 내 입계 및 입내에는 AlMgZn, AlMgFe 및 AlMgZnSi상 등 많은 양이 불균일하게 존재하며, 이들 상은 균질화처리 과정 중 입계 및 기지로 용해된다. 합금설계 프로그램 및 동력학 방정식을 활용한 결정립 내 주요 합금원소인 Mg 및 Zn의 확산거동을 분석한 결과, JMatPro 내 균질화처리 모드에서 대상합금 내 Mg이 Zn 대비 기지 내로 빠르게 용해되나, 동력학 방정식의 경우에도 유사한 경향성이 나타난다. 확산속도에 대한 의미로 실제로 Zn 대비 상대적으로 Mg이 많은 양을 함유하고 있어 기지로 확산과 동시에 고용되었음을 확인할 수 있었다.

• 한국재료학회지
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• 제20권2호
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• pp.60-64
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• 2010

This study looked at high performance copper-based alloys as LED lead frame materials with higher electrical-conductivity and the maintenance of superior tensile strength. This study investigated the effects on the tensile strength, electrical conductivity, thermal softening, size and distribution of the precipitation phases when Cr was added in Cu-Fe alloy in order to satisfy characteristics for LED Lead Frame material. Strips of the alloys were produced by casting and then properly treated to achieve a thickness of 0.25 mm by hot-rolling, scalping, and cold-rolling; mechanical properties such as tensile strength, hardness and electrical-conductivity were determined and compared. To determine precipitates in alloy that affect hardness and electrical-conductivity, electron microscope testing was also performed. Cr showed the effect of precipitation hardened with a $Cr_3Si$ precipitation phase. As a result of this experiment, appropriate aging temperature and time have been determined and we have developed a copper-based alloy with high tensile strength and electrical-conductivity. This alloy has the possibility for use as a substitution material for the LED Lead Frame of Cu alloy.

• 대한금속재료학회지
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• 제49권10호
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• pp.747-753
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• 2011

In order to improve the corrosion resistance of Fe-20Cr-1.7C-1Si hardfacing alloy without a loss of wear resistance, the effect of Ni addition was investigated. As expected, the corrosion resistance of the alloy increased with increasing Ni concentration. The wear resistance of the alloy did not decrease, even though the hardness decreased, up to Ni concentration of 5 wt.%. This was attributed to the fact that the decrease in hardness was counterbalanced by the strain-induced martensitic transformation. The wear resistance of the alloy, however, decreased abruptly with increases of the Ni concentration over 5 wt.%.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.411-414
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• 2005

It is reported that $\varepsilon$ (HCP) and $\gamma$ (FCC) phases of a Fe-17Mn alloy transform to $\alpha'$ phase, which has BCC structure, under a deformation condition. In this study, we investigated the effect of strain-induced-transformed $\alpha'$ phase on sliding wear of the Fe-17Mn alloy that originally had e and y phases. Wear tests of the materials were carried out using a pin-on-disk wear tester at various loads of 0.5N-50N under a constant sliding speed condition of 0.38m/s against glass $(83\%\;SiO_2)$ beads. The sliding distance and radius were loom and 9 mm, respectively. Wear rate of the Fe-17Mn alloy was calculated by dividing the weight loss, measured to the accuracy of $10^{-5}g$ by the measured specific gravity and sliding distance. Worn surface and wear debris of the specimens were examined using an SEM and XRD. During the wear, $\alpha'$ phase of BCC structure was formed by strain-induced transformation when the applied wear load exceeded critical values. The $\alpha'$ phase formed by the strain induced transformation increased the wear rate of the Fe-17Mn alloy.

• 한국주조공학회지
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• 제23권2호
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• pp.63-68
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• 2003

Al-Ti-C grain refiner form a relatively new alternative to the existing class of Al-Ti-B type grain refiners for achieving fine equiaxed structures in aluminum alloys during casting and solidification. The present study was carried out to investigate the influence of Al-Ti-C master alloys on the grain structure of Al-7Si alloys. The present study also investigates the relationship between grain refining efficiency and concentrations of Fe and Si in hypo-eutectic Al-Si alloys using Al-3Ti-0.13C master alloys. It is found that several parameters affect significantly the grain refining performance in silumin alloys. The present study reports the influence of various parameters such as alloy content, master alloy addition level, melt holding time and superheat on the grain refining efficiency in Al-7Si alloys.

• 한국자기학회지
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• 제23권3호
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• pp.83-88
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• 2013

두께 1 ${\mu}m$ 정도의 연자성 Fe-Si-Cr 합금 박편을 편상화 가공을 실시한 그대로 및 500과 $700^{\circ}C$에서 1시간 어닐링한 후 이를 폴리머 중에 분산시켜 준마이크로파 대역의 전자파 노이즈 억제용 복합 시트를 제조하여, 자성 합금의 열처리가 전자파 전송 손실(전력 손실)에 미치는 영향을 조사하였다. 합금 분말을 어닐링하지 않은 것이 어닐링한 분말을 사용한 경우보다 수 GHz의 주파수 대역에서 전력 손실의 크기가 증가하였다. 이 때 복소 투자율의 허수항 크기도 어닐링을 하지 않았을 때 더 큰 값을 나타내었는바 편상화 가공 상태의 자성 분말을 사용한 복합 시트가 우수한 전자파 노이즈 흡수 특성을 가지며, 이에는 그의 높은 복소 투자율의 허수항 크기가 기여하고 있는 것으로 판단되었다. 반면 편상화 시킨 합금 박편을 어닐링 한 경우에는 와전류 효과의 증대에 따라 복소 투자율이 낮아지고 따라서 전력 손실도 저하되는 것으로 생각되었다.

• 한국주조공학회지
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• 제35권5호
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• pp.120-127
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• 2015

The effects of Ti, B and Zr on grain refinement and castability were investigated in Al-4wt%Mg-0.9wt%Si-0.3wt%Mn-0.15wt%Fe alloy. Measurement of cooling curve and micro-structure observation were performed to analyze the effects of the addition of minor elements Ti, B and Zr during solidification. The prominence of effect on grain refinement was in increasing order for Ti, Zr and B element. Fine grain size and an increase of the crystallization temperature for ${\alpha}$-Al solution were evident as the amount of addition elements increased in this study. Addition of 0.15wt% Ti was most effective for grain refinement, and the resulting grain size of ${\alpha}$-Al solution for shell mold and steel mold were $72.3{\mu}m$ and $23.5{\mu}m$, respectively. Fluidity and shrinkage tests were perform to evaluate the castability of the alloy. Maximum fluidity length and minimum ratio of micro shrinkage were recorded for 0.15wt% Ti addition due to the effect of the finest grain size.

• 한국재료학회지
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• 제12권1호
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• pp.3-9
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• 2002

The corrosion behavior of alloys in a molten salt was investigated along with the oxidation characteristics in the air. The basic composition of alloys in the study was Fe-25Ni-7Cr with Si and RE(rare-earth metal) as additives. The corrosion rate of the alloys was low in a molten salt of LiCl while the rate was high in the mixed molten salt of LiCl and $Li_2O$. When Si is added to the base alloy of Fe-25Ni-7Cr, corrosion resistance was improved as the Si content is increased up to 3%, however, it was observed that the corrosion resistance was getting worse as the Si content is increased. The base alloy with 2.43% of Si and 0.9% of RE(KSA-65), showed higher corrosion rate compared to that of KSA-63 alloy with an equivalent amount of only Si. The corrosion resistance of KSA-65 was similar to that of the base alloy(KSA-60). The oxidation resistance of KSA-65 alloy was greatly increased even at $850^{\circ}C$ for a long term exposure.

• 한국주조공학회지
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• 제25권2호
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• pp.102-108
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• 2005

The ability and fading behavior of inoculant in ductile cast iron melt and the effect of minor element on them were investigated. The result obtanied on nodularization and the performance of inoculant were more distinct when the melt was treated and held at the high temperature range of $1450{\sim}1500^{\circ}C$ than at the lower one of $1350{\sim}1400^{\circ}C$. The performance of 5.2%Mg-Fe-Si alloy was the best of 4 nodularizers. That of Fe-75%Si(I) alloy was better than other 4 inoculants. The performance of the Fe-75%Si(I) inoculant was deteoriated by the addition of sulfur or bismuth. On the other hand, that was improved by the addition of cerium, even though its extent was not big.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.236-238
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• 1990

For improving magnetic properties of the amorphous Fe-B-Si alloy, we annealed in a magnetic field oriented in the plane of the ribbon longitudinal to its long axis. By field annealing, coercive force and total core loss are reduced from 0.04 Oe to 0.02 Oe, and from 0.25 watt/kg to 0.15 watt/kg respectively comparing with non-field annealed specimen. These reductions were caused by the formation of $180^{\circ}$ domains parallel to the annealing field due to the induced anisotorpy.