• 한국주조공학회지
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• 제20권6호
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• pp.395-399
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• 2000

The main interdendritic phase which was formed during early solidification of the ternary Mg-Zn-Ca alloys is the $Ca_2Mg_6Zn_3$ phase. The microstructure of $Mg-6wt%Zn-0.1{\sim}0.3wt%Ca$ alloys consisted of MgZn precipitates and $Ca_2Mg_6Zn_3$ phase formed around the grain boundaries. In the alloys with the highest level of Ca($Mg-6wt%Zn-0.5{\sim}0.7wt%aCa$ alloys), the microstructure revealed wholly $Ca_2Mg_6Zn_3$ phase formed around the grain boundaries. The grain size of Mg-6wt%Zn-Ca alloys decreased significantly with increase in Ca content and, at 0.5wt% Ca or more, grain size becomes constant at about 60 ${\mu}m$. The tensile properties of the as-cast Mg-6wt%Zn-Ca magnesium alloys were improved due to grain refinement by addition of Ca.

• 한국주조공학회지
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• 제38권4호
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• pp.75-81
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• 2018

This study examined the effect of the CaMgSn ternary phase on the aging response of the Mg-Sn-Zn alloy. The results revealed that the CaMgSn ternary phase formed in rod-like or needle-like shapes in Mg-3Zn-0.3Ca-xSn (x=1.5, 3, and 5 wt%) alloys and its size decreased as the Sn content increased from 1.5 wt% to 5 wt%. The Mg-3Zn-0.3Ca-5Sn alloy with a relatively fine CaMgSn phase was subjected to solution heat treatment and an aging process. Both the Mg-5Sn-3Zn-0.3Ca and Mg-5Sn-3Zn (base alloy) alloys had similar peak hardness values throughout all aging temperatures but the time-to-peak hardness in the Mg-5Sn-3Zn-0.3Ca alloy was 24-36 hours-earlier than that in the base alloy. Precipitates in the Mg-5Sn-3Zn-0.3Ca alloy were more refined than those in the Mg-5Sn-3Zn alloy and were mostly formed on basal planes. The $Mg_2Sn$ phase formed in either plate-like or rod-like shapes in the Mg-5Sn-3Zn alloy, whereas block-shaped $Mg_2Sn$ particles also formed in the Mg-5Sn-3Zn-0.3Ca alloy.

• 한국재료학회지
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• 제7권11호
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• pp.1012-1017
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• 1997

Mg-Zn-Ca합금의 잉곳트는 BN을 내벽에 바른 4x$10^{-5}$Torr의 진공의 석영관내에서 제조하였다. Mg-Zn합금계의 입자미세화를 위하여 0.5-5wt.%조성범위의 Ca를 첨가하였다. 제조된 합금을 용체화처리한 후 결정립크기와 경도를 측정하였다. Mg-6wt.%Zn합금의 입자미세화효과는 Ca가 1.5wt%첨가 될 때 최적의 조건이었다. Mg-6wt.% Zn과 Mg-6wt.% Zn-2wt.% Ca및 Mg-6wt.% Zn-1.5wt.% Si합금을 시효처리하여 시효거동을 조사하였다. 입자미세화에 의한 경도증가효과는 Mg-Zn-Ca합금계에서 크게 나타났으며 시효에 의한 경도증가효과는 Mg-Zn-Si합금계에서 크게 나타났다. Mg-6wt.%Zn합금의 부식전류밀도는 0.5wt.% Ca의 조성에서 감소되었다.

• 한국식품영양과학회지
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• 제27권5호
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• pp.928-934
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• 1998

The purpose of this study was to investigate differences of Ca, Mg and Zn utilization in young and adult rats fed standard diet for 3 weeks. Feed intake and body weight gain in young rats were significantly higher than in adult. There were no significant differences in serum levels of Ca and Zn across age and sex. In liver of young or male groups, Ca and Zn contents were significantly higher than in adult or female. There were no significant differences in tibia contents of Ca and Mg, but Zn content was increased when young or female groups was compared with the other groups. In mineral balances, daily intakes and retentions of Ca, Mg and Zn in young or male groups were significantly higher than those in adult or female. According to this results, it could be suggested that in growth period must be increased dietary intake of Ca, Mg and Zn to compromise the requirement for growth.

• 한국주조공학회지
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• 제26권2호
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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.

• 한국재료학회지
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• 제25권6호
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• pp.269-273
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• 2015

The effect of adding Ca on the microstructural and mechanical properties of as-cast Mg-11Li-3Zn-1Sn(wt%) alloys were investigated. Mg-11Li-3Zn-1Sn-0.4Mn with different Ca additions (0.4, 0.8, 1.2 wt%) were cast under an $SF_6$ and $Co_2$ atmosphere at $720^{\circ}C$. The cast billets were homogenized at $400^{\circ}C$ for 12h and extruded at $200^{\circ}C$. The microstructural and mechanical properties were analyzed by OM, XRD, SEM, and tensile tests. The addition of Ca to the Mg-11Li-3Zn-1Sn-0.4Mn alloy resulted in the formation of $Ca_2Mg_6Zn_3$, MgSnCa intermetallic compound. By increasing Ca addition, the volume fraction and size of $Ca_2Mg_6Zn_3$ with needle shape were increased. This $Ca_2Mg_6Zn_3$ intermetallic compound was elongated to the extrusion direction and refined to fine particles due to severe deformation during hot extrusion. The elongation of the 0.8 wt% Ca containing alloy improved remarkably without reduction strength due to the formation of fine grain and $Ca_2Mg_6Zn_3$ intermetallic compounds by Ca addition. It is probable that fine and homogeneous $Ca_2Mg_6Zn_3$ intermetallic compounds played a significant role in the increase of mechanical properties.

• 한국주조공학회지
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• 제40권2호
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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.

• 한국분말재료학회지
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• 제12권4호
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• pp.303-308
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• 2005

Various kinds of Mg-Zn-Ca base alloys were rapidly quenched via melt spinning process. The meltspun ternary and quaternary alloy ribbons were heat-treated, and then the effects of additional elements on age hardening behavior and phase change of precipitates were investigated using Vickers hardness tester, XRD, and TEM equipped with EDS system. In ternary alloys, age hardening was mostly due to the distribution of $Mg_6Ca_2Zn_3$ and $Mg_2Ca$. The stable phases of precipitates were varied according to the aging temperature and the alloy composition. With the increase of Ca content, $Mg_2Ca$ precipitates were detected more than $Mg_6Ca_2Zn_3$ precipitates. In quaternary alloys, the precipitates taken from Mg-Zn-Ca-Co were identified as new quaternary phase, whereas those taken from Mg-Zn-Ca-Zr as MgZnCa containing Zr. In general, the ternary alloy showed higher peak hardness and thermal stability than the quaternary considering the total amounts of the solutes. It implies that the structure of precipitate should be controlled to have the coherent interface with the Mg matrix.

• 열처리공학회지
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• 제29권4호
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• pp.168-175
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• 2016

Influence of trace amount of Ca addition on the corrosion resistance was comparatively investigated in solutionized Mg-4%Zn and Mg-4%Zn-0.1%Ca alloys. In as-cast state, the alloys were characterized by primary ${\alpha}-(Mg)$ dendrite with MgZn intermetallic compound particles. After solution-treatment, both alloys consisted of single ${\alpha}-(Mg)$ phase by dissolution of the compound particles into the matrix. It was found from the immersion and electrochemical corrosion tests that the Mg-4%Zn alloy had better corrosion resistance than the Mg-4%Zn-0.1%Ca alloy. Morphological and compositional analyses on the surface corrosion products indicate that the incorporation of Ca oxide with low PBR value into the surface corrosion products would be responsible for the decreased corrosion resistance of the Ca-containing alloy.

• 한국주조공학회지
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• 제35권6호
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• pp.155-162
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• 2015

The effect of Sr addition on mechanical and bio-corrosion properties of as-cast Mg-3wt.%Zn-0.5wt.%Ca-xwt.%Sr (x = 0.3, 0.6, 0.9) alloys were examined for application as biodegradable implant material. The microstructure, mechanical properties and corrosion resistance of the as-cast Mg-Zn-Ca-Sr alloys were characterized by using optical microscopy, scanning electron microscopy, tensile testing and electrochemical measurement in Hank's solution. The as-cast alloys contained ${\alpha}$-Mg and eutectic $Ca_2Mg_6Zn_3$ phases, while the alloys contained ${\alpha}$-Mg, $Ca_2Mg_6Zn_3$ and Mg-Zn-Ca-Sr intermetallic compound when the Sr addition was more than 0.3 wt.%. The yield strength, ultimate tensile strength and elongation increased with the increasing of Sr content up to 0.6 wt.% but decreased in the 0.9 wt.% Sr-added alloy, whereas the corrosion resistance of 0.3 wt.% Sr-added alloy was superior to other alloys. It was thought that profuse Mg-Zn-Ca-Sr intermetallic compound deteriorated both the mechanical properties and corrosion resistance of the as-cast alloy.