• Title/Summary/Keyword: Mg-Zn-Y alloy

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Development of High Strength Mg-Zn-Gd Alloys by Rapid Solidification Processing

  • Kim, Min-Chul;Yamasaki, Michiaki;Kawamura, Yoshihito
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1048-1049
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    • 2006
  • Rapidly solidified ribbon-consolidation processing was applied for preparation of high strength bulk Mg-Zn-Gd alloys. Mg alloys have been used in automotive and aerospace industries. Rapid solidification (RS) process is suitable for the development of high strength Mg alloys, because the process realizes grain-refinement, increase in homogeneity, and so on. Recently, several nanocrystalline Mg-Zn-Y alloys with high specific tensile strength and large elongation have been developed by rapidly solidified powder metallurgy (RS P/M) process. Mg-Zn-Y RS P/M alloys are characterized by long period ordered (LPO) structure and sub-micron fine grains. The both additions of rare earth elements and zinc remarkably improved the mechanical properties of RS Mg alloys. Mg-Zn-Gd alloy also forms LPO structure in -Mg matrix coherently, therefore, it is expected that the RS Mg-Zn-Gd alloys have excellent mechanical properties. In this study, we have developed high strength RS Mg-Zn-Gd alloys with LPO structure and nanometer-scale precipitates by RS ribbon-consolidation processing. $Mg_{97}Zn_1Gd_2$ and $Mg_{95.5}Zn_{1.5}Gd_3$ and $Mg_{94}Zn_2Gd_4$ bulk alloys exhibited high tensile yield strength (470 MPa and 525 MPa and 566 MPa) and large elongation (5.5% and 2.8% and 2.4%).

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The Effect of Al and Sn Additions on Corrosion Behavior of Permanent Mold Casting Magnesium Alloy (금형 주조한 마그네슘 합금의 부식 거동에 미치는 Al 및 Sn의 영향)

  • Kim, Byeong Ho;Seo, Jae Hyun;Park, Kyung Chul
    • Journal of Korea Foundry Society
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    • v.35 no.2
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    • pp.36-43
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    • 2015
  • In this study, the influences of aluminum and tin additions (individual and combined) on corrosion behavior of magnesium alloy have been determined. The studied alloys were fabricated by permanent mold casting method to measure the corrosion properties, a potentiodynamic test, hydrogen evolution test and immersion test were carried out in a 3.5% NaCl solution at pH 7.2. From the results of microstructure analysis, the Mg-9Al-1Zn alloy was found to be composed of ${\alpha}$-Mg and rod-like $Mg_{17}Al_{12}$ phase and the Mg-5Sn-5Al-1Zn alloy was found to be composed of ${\alpha}$-Mg, rod-like $Mg_{17}Al_{12}$ and $Mg_2Sn$ phases. In the case of the Mg-9Sn-1Zn alloy, the microstructure was composed of ${\alpha}$-Mg and eutectic $Mg_2Sn$ phase. With Sn addition (individual and combined), the corrosion resistance of the Mg alloys improved.

Effect of Cu Addition on Thermal Properties of Mg-6Zn-xCu alloys (Mg-6Zn-xCu 합금의 열적 특성에 미치는 Cu 첨가의 영향)

  • Ye, Dea-Hee;Kim, Hyun-Sik;Kang, Min-Cheol;Jeong, Hae-Yong
    • Journal of Korea Foundry Society
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    • v.35 no.4
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    • pp.67-74
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    • 2015
  • In this study, Mg-Zn alloys are investigated in terms of their thermal properties after an addition of Cu. Al element is added to improve the mechanical properties and castability in general case. However, it was excluded here because it significantly decreases the thermal conductivity. On the other hand, Zn was added as a major element, which had less influence on reducing the conductivity and can complement the mechanical properties as well. Cu was also added, and it improved the heat transfer characteristics as the amount was increased. The composition ranges of Zn and Cu are 6 wt.% and 0~1.5 wt.%, respectively. Mg-6Zn-xCu alloy was prepared by a gravity casting method using a steel mold and then the thermal conductivity and the microstructure of the as-cast material were investigated. By measuring the density_(${\rho}$), specific heat_(Cp) and thermal diffusivity_(${\alpha}$), the thermal conductivity_(${\lambda}$) was calculated by the equation ${\lambda}={\rho}{\cdot}Cp{\cdot}{\alpha}$. As the amount of Cu increased in the Mg-6Zn-xCu alloy, the heat transfer characteristics were improved, resulting in a synergistic effect which is slow when the added Cu exceeds 1 wt.%. In order to investigate the relative thermal conductivity/emission of the Mg-6Zn-xCu alloy, AZ91 and AZ31 were experimentally evaluated and compared using a separate test equipment. As a result, the Mg-6Zn-1.5Cu alloy when compared to AZ91 showed improvements in the thermal conductivity ranging from 30 to 60% with a nearly 20% improvement in the thermal emission.

A study of galvanic characteristics of aluminium alloy anode in the Al-Zn-In-Mg system made of the low purity aluminium ingot (저순도 Al지금을 사용한 Al-Zn-In-Mg계 Al합금 유전양극의 특성에 관한 연구)

  • 김원녕;김기준;김영대
    • Journal of Advanced Marine Engineering and Technology
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    • v.9 no.3
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    • pp.240-249
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    • 1985
  • This paper presents the results of the galvanic anode's characteristicsin the Al-Zn-In-Mg and Al-Zn-In-Mg system anodes used aluminium ingot of low purity, 99.5% grade. The results of thses performance tests are as follows: 1) Zn, In and Mg are an available elements to improve the performance of Aluminium alloy anodes. 2) When the range of zinc content in the Al-Zn-In-Mg system anode is 2-5% the more zinc content, the more improve the anode performance. 3) Al-Zn-In-Mg system anode requires a long term over 50 days for the performance test. 4) The composition of Al-Zn-In-Mg system anode which shows the most excellent performance is Al-(2-3%) Zn-(0.02%) In-(1.0%) Mg. 5) When the Al-Zn-In-Mg system anode is annealed for an hour in 500 to 550 .deg. C, the anode performance is improved. 6) The lower average potential and the better corrosion pattern in the Al-Zn-Mg, Al-Zn-In and Al-Zn-In-Mg system anodes, the more current efficiency is improved.

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Stress Corrosion Cracking of High Strength Al-Zn-Mg-Cu Aluminum Alloy with Different Compositions (고강도 Al-Zn-Mg-Cu 합금에서 조성에 따른 응력부식균열 특성)

  • Kim, Jun-Tak;Kim, Sang-Ho
    • Journal of the Korean institute of surface engineering
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    • v.41 no.3
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    • pp.109-113
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    • 2008
  • High strength 7xxx series Al-Zn-Mg alloy have been investigated for using light weight automotive parts especially for bump back beam. The composition of commercial 7xxx aluminum has the Zn/Mg ratio about 3 and Cu over 2 wt%, but this composition isn't adequate for appling to automotive bump back beam due to its high resistance to extrusion and bad weldability. In this study the Zn/Mg ratio was increased for better extrusion and Cu content was reduced for better welding. With this new composition we investigated the effect of composition on the resistivity against stress corrosion cracking. As the Zn/Mg ratio is increased fracture energy obtained by slow strain rate test was decreased, which means degradation of SCC resistance. While the fracture energy was increased with Cu contents although it is below 1%, which means improvement of SCC resistance. These effects of composition change on the SCC resistivity were identified by observing the fracture surface and crack propagation.

The Effect of Ca Addition on Creep Behavior of As-cast Mg-8.0Zn-1.6Y Alloys with Icosahedral Phase (Icosahedral 상을 갖는 Mg-8Zn-1.6Y 합금의 크리프 거동에 미치는 Ca 첨가 영향)

  • Jung, Young-Gil;Yang, Wonseok;Kim, Shae K.;Lim, Hyunkyu;Oh, Gun-Young;Kim, Youngkyun;Kim, Do Hyang
    • Journal of Korea Foundry Society
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    • v.40 no.2
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    • pp.7-15
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    • 2020
  • The high-temperature stability of Mg-8.0Zn-1.6Y (wt.%) alloys upon the addition of Ca has been investigated by characterizing the ignition temperature, microstructure, tensile and creep properties. The ignition temperature increases with an increase in the Ca content, indicating that an addition of Ca enhances the ignition resistance of the Mg-Zn-Y alloy. The as-cast microstructures of all tested alloys mainly consisted of the dendritic α-Mg matrix and I-phase (Mg3Zn6Y) at the grain boundaries. In the Ca-added Mg-8.0Zn-1.6Y alloys, the Ca2Mg6Zn3 phase forms, with this phase fraction increasing with an increase in the Ca contents. However, a high volume fraction of the Ca2Mg6Zn3 phase rather deteriorates the mechanical properties. Therefore, a moderate amount of Ca element in Mg-8.0Zn-1.6Y alloys is effective for improving the tensile and creep properties of the Mg-Zn-Y alloy. The Mg-8.0Zn-1.6Y-0.3Ca alloy exhibits the highest tensile strength and the lowest creep strain among the alloys investigated in the present study. The creep resistance of Mg-Zn-Y-Ca alloys depends on the selection of the secondary solidification phase; i.e., when Ca2Mg6Zn3 forms in an alloy containing a high level of Ca, the creep resistance deteriorates because Ca2Mg6Zn3 is less stable than the I-phase at a high temperature.

Glass Forming Ability and Characteristic Evaluation in Ca-Mg-Zn Alloy System (Ca-Ma-Zn 합금계에서 비정질 형성능 및 특성 평가)

  • Park, Eun-Soo;Kim, Won-Tae;Kim, Do-Hyang
    • Journal of Korea Foundry Society
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    • v.26 no.2
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    • pp.77-84
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    • 2006
  • The effect of alloy composition on the glass forming ability (GFA) of the Ca-rich Ca-Mg-Zn alloys has been investigated in $Ca_{65}Mg_{5+x}Zn_{30-x}$ and $Ca_{55+x}Mg_{15}Zn_{30-x}$ (x=0, 5, 10, 15, 20) alloys. In a wide composition range of 15-25% Zn and 10-20% Mg bulk metallic glass (BMG) samples with the diameter larger than 6 mm are fabricated by conventional copper mold casting method in air atmosphere. Among the alloys investigated, the $Ca_{65}Mg_{15}Zn_{20}$ alloy exhibits the highest GFA enabling to form BMG sample with the diameter of at least 15 mm. The crystalline phase formed during solidification of $Ca_{65}Mg_{15}Zn_{20}$ ($D_{max}=15\;mm$) could be identified as a mixture of $Ca_3Zn$ and $CaMg_2$ cause by the redistribution of the constituent elements on long-range scale. The compressive fracture strength and fracture elongation of the $Ca_{65}Mg_{15}Zn_{20}$ BMG are 602 MPa and 2.08% respectively. The ${\sigma}$ parameter which has been recently proposed for evaluating GFA exhibits better correlation with GFA of Ca-Mg-Zn alloys than other parameters suggested so far such as ${\Delta}T_x$, $T_{rg}$, K, ${\gamma}$, and ${\Delta}T^*$ parameters.

Investigations on electron beam weldability of AlZnMgCu0.5 alloys (AlZnMgCu0.5 합금의 Electron Beam 용접성에 관한 연구)

  • 배석천
    • Journal of Welding and Joining
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    • v.15 no.4
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    • pp.166-177
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    • 1997
  • The high strength AlZnMgCu0.5 alloy is a light metal with good age hardenability, and has a high tensile and yielding strength. Therefore, it can be used for structures requiring high speciple strength. Even though high strength AlZnMgCu alloy has good mechanical properties, it has a lot of problems in TIG and MIG welding processes. Since lots of high heat absorption is introduced into the weldment during TIG and MIG processes, the microstructural variation and hot cracks take place in heat affected zone. Therefore, the mechanical properties of high strength AlZnMgCu0.5 alloy can be degraded in weldment and heat affected zone. Welding process utilizing high density heat source such as electron beam should be developed to reduce pore and hot cracking, whichare usually accompanied by MIG and TIG welding processes. In this work, electron beam welding process were used with or without AlMg4.5Mn as filler material to avoid the degradation of mechanical properties. Mechanical and metallurgical characteristics were also studied in electron beam weldment and heat affected zone. Moreover hot cracking mechanism was also investigated.

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Extrusion Behavior of Gas Atomized Mg Alloy Powders (가스분무 Mg-Zn-Y 합금분말의 압출거동)

  • Chae, Hong-Jun;Kim, Young-Do;Lee, Jin-Kyu;Kim, Jeong-Gon;Kim, Taek-Soo
    • Journal of Powder Materials
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    • v.14 no.4
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    • pp.251-255
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    • 2007
  • This work is to report not only the effect of rapid solidification of $MgZn_{4.3}Y_{0.7}$ alloys on the micro-structure, but also the extrusion behavior on the materials properties. The average grain size of the atomized powders was about $3-4{\mu}m$. The alloy powders of $Mg_{97}Zn_{4.3}Y_{0.7}$, consisted of I-Phase (Icosahedral, $Mg_{3}Zn_{6}Y_{1}$) as well as Cubic structured W-Phase ($Mg_{3}Zn_{3}Y_{2}$), which was finely distributed within ${\alpha}-Mg$ matrix. The oxide layer formed along the Mg surface was about 48 nm in thickness. In order to study the consolidation behavior of Mg alloy powders, extrusion was carried out with the area reduction ratio of 10:1 to 20:1. As the ratio increased, fully deformed and homogeneous microstructure could be obtained, and the mechanical properties such as tensile strength and elongation were simultaneously increased.