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- 저자 : 홍종휘 ( Hyun Kyu Lee (검색결과 3 건)
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Al-CuAl2 공정복합재료의 기계적 성질에 미치는 응고조건과 열처리의 영향
이현규,이주홍,홍종휘 ( Hyun Kyu Lee,Ju Hong Lee,Jong Hwi Hong ) 한국주조공학회 1990 한국주조공학회지 Vol.10 No.4
N/A The structure and tensile properties of the unidirectionally solidified Al-33wt.%Cu alloy have been investigated. Casted Al-33wt.%Cu alloy was unidirectionally solidified with rates (R) between 1㎝/hr and 24㎝/hr maintaining the thermal gradient(G) at solid-liquid interface, 32℃/㎝ and 21℃/㎝. The entectic struture was varied according to the growth condition(G/R radio). When G/R ratio was larger than 8.5×10³℃/㎠ /sec the lamellar structure was formed, and colony structure was formed when G/R ratio was smaller than 8.5×10³℃/㎠ /sec. The interlamellar spacing(λ) in the above alloy system was vaired with the growth rate(R) According to λ²·R=8.8 × 10^(-11)㎤ /sec relationship. The yield stress (σ0.001) and UTS for samples in the as-grown condition increased with the interlamellar spacing decrease and the values corresponding to colony structure are lower than those corresponding to amellar structure with the same lamellar spacing. The yield stress for samples in aged condition did not change with the interlamellar spacing.
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질화물강화 Al-Li 합금 복합재료의 제조 및 기계적 성질
이현규,홍종휘,홍영환,이승만 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.1
In this study we have tried to fabricate nitride particle-reinforced composite materials through blowing nitrogen gas into Al-Li alloy melts, and identified the formation of nitride particles such as AlN and Li₃N. The average size of AlN and Li₃N dispersoids formed by nitriding reaction were a few ㎛ and nm order, respectively. The addition of Mg appeared to be effective to facilitate the nitriding reaction and to prevent the loss of Li due to deoxidation in the melt. And the tensile strengths of these N₂ gas-blowed composites were greatly increased compared to that of unblowed Al-Li alloy. Therefore it is clear that the formation of nitride particles had a great effect on the increase of tensile strength of the composites. However, long time blowing of more than 20 minutes resulted in a decrease of tensile strength due to the removal of preformed nitrides by the blowing gas. Ductility, which is a major problem of Al-Li alloys, is also greatly improved by this process compared to that of conventional Al-Li alloys.
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이현규,홍종휘,홍영환,박정민 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.7
In the present study, we made an attempt to fabricate a nitride-reinforced Al alloy composite by blowing N₂gas into Al alloy melts. The addition of reactive element Mg to Al alloy melt facilitated the nitriding reaction, leading to the formation of TiN in Al-5wt.%Ti-10wt.%Mg alloy, but rarely formed in Al-5wt.%Ti alloy due to the absence of Mg. The former alloy showed higher room temperature tensile strength as compared with the latter alloy, which is mainly due to the presence of TiN and partly due to solid solution strengthening effects of Mg. In addition, it is considered that the presence of nitride may also be responsible for high temperature strengthening, judging from the lower decreasing rate of tensile strength with temperature in Al-5wt.%Ti-10wt.%Mg alloy.
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