• 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.

• 대한금속재료학회지
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• 제47권8호
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• pp.474-481
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• 2009

The effects of final heat treatment on the mechanical and corrosion properties of a Zr alloy strip incorporating Nb were investigated. The chemical composition of the strip was Zr-1.49Nb-0.38Sn-0.20Fe-0.11Cr, and strip specimens were subjected to final heat treatment in a temperature range of $580{\sim}700^{\circ}C$. Tensile tests at room temperature and $316^{\circ}C$, along with corrosion tests in a simulated PWR loop and a 70 ppm LiOH solution environment at $360^{\circ}C$, were performed on the specimens. The mechanical properties of the strip were saturated when the specimens received final heat treatment at an elevated temperature of more than $640^{\circ}C$. However, the corrosion resistance of the strip in the simulated PWR loop and in the 70 ppm LiOH solution environment was improved with a decrease of the final annealing temperature. It is recommended that the alloy strip be finally heat-treated at a temperature of less than $620^{\circ}C$ for longer than 10 minutes in order to obtain fully recrystallized microstructures, and thereby attain enlarged tensile elongation, and to prevent the precipitation of ${\beta}-Zr$, which is known to deteriorate the corrosion resistance.

• 한국재료학회지
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• 제33권1호
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• pp.8-14
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• 2023

In order to broaden the range of application of light weight aluminum alloys, it is necessary to enhance the mechanical properties of the alloys and combine them with other materials, such as cast iron. In this study, the effects of adding small amounts of Cu and Zr to the Al-Si-Mg based alloy on tensile properties and corrosion characteristics were investigated, and the effect of the addition on the interfacial compounds layer with the cast iron was also analyzed. Although the tensile strength of the Al-Si-Mg alloy was not significantly affected by the additions of Cu and Zr, the corrosion resistance in 3.5 %NaCl solution was found to be somewhat lowered in this research. The influence of Cu and Zr addition on the type and thickness of the interfacial compounds layer formed during compound casting with cast iron was not significant, and the main interfacial compounds were identified to be Al₅FeSi and Al₈Fe₂Si phases, as in the case of the Al-Si-Mg alloys.

• 한국재료학회지
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• 제8권1호
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• pp.3-9
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• 1998

40$0^{\circ}C$ H$_{2}$O, D$_{2}$O및 $O_{2}$분위기에서 Zr-2.5Nb합금의 부식거동을 분석하였다. Martensitic $\alpha$'-Zr상이나 $\alpha$-Zr과 $\beta$-Zr상의 Zr-2.5Nb합금인 경우, 부식분위기에 매우 민감하여, $O_{2}$속에서 가장 큰 부식속도를 보였다. 반면, $\alpha$-Zr나 $\beta$-Zr상의 경우, 부식 매질에 따른 별다른 차이없이 높은 부식저항성을 보였다. 이러한 Zr-2.5Nb 합금의 미세조직 및 부식 매질에 따른 부식거동변화는 Zr-2.5Nb 합금의 음극 지배 부식반응의 관점으로 해석되었으며, 이들 결과를 이용하여 CANDU 형및 RBMK 형 Zr-2.5Nb 압력관의 가동조건 차이를 설명할 수 있었다. Zr-2.5Nb 합금의 모든 조직에서 주로 단사정 ZrO$_{2}$산화물이 형성되었으며, 산화물내 정방정 ZrO$_{2}$비율은 산화물 두께가 증가함에 따라 감소하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.269.1-269
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• 2002

• 한국주조공학회지
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• 제15권2호
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• pp.194-200
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• 1995

Rapidly Solidified (RS) Al-Zr base splats with various alloy contents were prepared by atomization-splat quenching method to understand the continuous and discontinuous precipitation in the aged alloys. And the RS alloys were consolidated by hot extrusion and swaging to analyze the effect of plastic deformation on the precipitation behavior. Discontinuous precipitation dominated at relatively low temperature in the Al-Zr alloy, whereas both V additions to Al-Zr alloys and hot metal working appeared to suppress the discontinuous precipitation. As continuous precipitation is favored in the grain interiors, the driving force for discontinuous precipitation become to disappear with a further process.

• 한국수소및신에너지학회논문집
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• 제2권1호
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• pp.39-46
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• 1990

In order to improve the power of hydride heat pump, prototype heat pump was constructed using $Zr_{0.95}Ti_{0.05}Cr_{0.9}Fe_{1.1}$-$Zr_{0.9}Ti_{0.1}Cr_{0.6}Fe_{1.4}$ which had very good hydrogenation properties. The power changed with operating parameter such as cycle time, air flow rate, and temperature of hot air was investigated. The power shows maximum value with cycle time. The power increased with air flow rate and temperature of hot air. The power of the heat pump was $65-72 Kcal/Kg-alloy{\cdot}h$ under optimum operating condition, which was superior to that the system using $LaNi_{0.9}Al_{0.3}-MmNi_{4.15}Al_{0.66}Fe_{0.2}$ alloy pairs.

• 대한치과기공학회지
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• 제26권1호
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• pp.41-48
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• 2004

Ti-20%Zr(-5%Cr) alloys not containing harmful Al and V were newly designed in order to reveal their possibility for dental casting and melted in an arc melting and casting furnace under Ar atmosphere. The corrosion resistance was studied by anodic polarization test. From the observation of anodic polarization behavior, it was found that the corrosion resistance was markedly increased by the addition of Cr. The corrosion resistance of Ti-20%Zr-5%Cr alloy was superior to that in Ti-6%Al-4%V alloy but almost similar to that in CP Ti using in market place today.

• Applied Microscopy
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• 제45권2호
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• pp.58-62
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• 2015

Formation of an icosahedral phase in the bulk glass forming $Ti_{40}Zr_{29}Be_{14}Cu_9Ni_8$ alloy during crystallization from amorphous phase and solidification from melt is investigated. The icosahedral phase with a size of 10 to 15 nm forms as a thermodynamically stable phase at intermediate temperature during the transformation from amorphous to crystalline phases such as Laves and ${\beta}$-(Ti-Zr) phases, indicating that the existence of the icosahedral cluster in the undercooled liquid. On the other hand, the icosahedral phase forms as a primary solidification phase even though the Laves phase is stable at high temperature, which is can be explained based on the high nucleation rate of icosahedral phase relative to that of competing crystalline Laves phase due to lower interfacial energy between icosahedral and liquid phases.

• Corrosion Science and Technology
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• 제8권4호
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• pp.139-142
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• 2009

Recently, quaternary titanium alloys of the system Ti-Nb-Ta-Zr received considerable research interest as potential implant materials because of their excellent mechanical properties and biocompatibility. However, only few reported works were available on the corrosion behavior of such alloys. Hence, in the present work, electrochemical corrosion of Ti-35Nb-5Ta-7Zr alloy, which has been fabricated by arc melting and heat treatment, was studied in 0.9 wt% NaCl at $37\pm1^{\circ}C$, along with biomedical grade Ti-6Al-4V and CP-Ti. The phase and microstructure of the alloys were investigated employing XRD and SEM. The results of electrochemical studies indicated that the corrosion resistance of the quaternary alloy was inferior to that of Ti-6Al-4V and CP Ti.