기계적 합금화과정에서의 in situ 열분석에 의한 Ti-50.0~66.7at%Si 분말의 합성거동

변창섭,이상호,이원희,현창용,김동관,Byun Chang Sop,Lee Sang Ho,Lee Wonhee,Hyun Chang Yong,Kim Dong Kwan 한국재료학회 2004 한국재료학회지 Vol.14 No.5

Mechanical alloying (MA) of Ti-50.0~66.7at%Si powders was carried out in a high-energy ball mill, and in situ thermal analysis was also made during MA. In order to classify the synthesis behavior of the powders with respect to at%Si, the synthesis behavior during MA was investigated by in situ thermal analysis and X-ray diffraction (XRD). In situ thermal analysis curves and XRD patterns of Ti-50.0~59.6at%Si powders showed that there were exothermic peaks during MA, indicating TiSi, $TiS_2$, and $Ti_{5}$ $Si_4$ phase formation by a rapid exothermic reaction of self-propagating high-temperature synthesis (SHS). Those of Ti-59.8~66.7 at%Si powders, however, showed that there were no peaks during MA, indicating any Ti silicide was not synthesised until MA 240 min. For Ti-50.0~59.6at%Si powders, the critical milling times for SHS increased from 34.5 min to 89.5 min and the temperature rise, $\Delta$T (=peak temperature-onset temperature) decreased form $26.2^{\circ}C$ to $17.1^{\circ}C$ as at%Si increased. The critical composition of Si for SHS reaction was found to be 59.6at% and the critical value of the negative heat of formation of Ti-59.6at%Si to be -1.48 kJ/g.

원료분말과 금속간화합물 분말로 기계적 합금화한 $Al_3$(${Nb_{1-x}}{Zn_x}$) 합금의 미세구조특성

이광민,이지성,안인섭,Lee, Gwang-Min,Lee, Ji-Seong,An, In-Seop 한국재료학회 2001 한국재료학회지 Vol.11 No.5

본 연구에서는 MA 방법을 사용하여 $Al_3$Nb 금속간화합물의 조성에 Zr을 첨가하여 $Al_3$(Nb$_{1-x}$ )Zr$_{x}$ 합금분말을 제조한 후 이에 따른 상변화 거동 및 미세구조특성을 분석하였다. MA는Al$_3$(Nb$_{1-x}$ )Zr$_{x}$의 조성으로 Al, Nb, Zr 원료분말과 arc meltinly된 $Al_3$Nb, $Al_3$Zr 금속간화합물 분말을 사용하여 300rpm의 회전속도로 20시간 동안 MA하였다. 이때의 정상상태의 원료분말은 약 4$\mu\textrm{m}$의 평균입도와 약 12~18nm의 결정립크기를 가졌으며, arc melting된 분말은 약 2$\mu\textrm{m}$의 평균입도와 약 14nm의 결정립크기를 가지는 분말을 얻을 수 있었다 원료분말과 금속간화합물 분말의 MA 기구는 상이한 거동을 나타내었으며, 분말의 내부변형량은 원료분말이 금속간화합 분말보다 내부변형량이 더 많이 축적되었다. 이는 원료분말의 MA 경우 냉간 압접과 파괴가 반복적으로 진행되었지만 금속간화합물 분말은 취약한 화합물상이어서 냉간압접 보다는 파괴가 지배적으로 진행되었기 때문이다. 원료분말을 MA하였을 경우에는 Al (Nb.Zr)$_2$상이 형성되었으나 금속간화합물 분말로 MA하였을 경우에는 3원계 화합물상이나 비정질상으로 상변태 되지 않고 단지 두 합금상이 분쇄되어 나노복합화 되었다. 후속 열처리에 의해 원료분말인 경우에는 $Al_3$(Nb.Zr)의 화합물상이 쉽게 형성되었으나, 금속간화합물 분말의 경우에는 새로운 상 생성은 얼었고 단지 열처리 전의 분말내부에 쌓여있던 내부변형에너지가 약 60% 정도 감소하였다. The present study was carried out to investigate the effect of zirconium addition to $Al_3$Nb intermetallic on the crystal structural modification and microstructural characterization of $Al_3$Nb intermetallic. Elemental Al, Nb, Zr powders and arc melted $Al_3$Nb and $Al_3$Zr intermetallic mixed powders were used as starting materials. MA was carried out in an attritor rotated with 300 rpm for 20 hours. The behavior of MA between two starting materials was some-what different in which the value of internal strain of the elemental powders was higher than that of the intermetallic powder. The intermetallic powder was much more disintegrated during the MA processing. In the case of the elemental powders, AlNb$_2$ phase were transformed to Al(Nb.Zr)$_2$ as a result of ternary addition of Zr element. With the successive heat treatment at 873K for 2 hours, the Al(Nb.Zr)$_2$ phase was transformed to more stable $Al_3$(Nb.Zr) phase. This transformation was clearly confirmed by the identification of X-ray peak position shift. On the other hand, in the carte of the intermetallic powder, there was no evidence of phase transformation to other ternary intermetallic compounds or amorphous phases, even in the case of additional heat treatment. However, nano-sized intermetallic with $Al_3$Nb and $Al_3$Zr were just well distributed instead of phase transformation.

나노사이즈-산화물 분산강화 Fe-17% Cr 페라이트계 합금의 고온인장 성질에 미치는 미세조직의 영향

김익수,Watanabe, Y.,이용복,장진성,김창룡,Miyahara, K. 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.2

In the past few years, oxide dispersion strengthened(ODS) alloys produced by mechanical alloying(MA) techniques have become increasingly interesting for structure applications in nuclear fission and fusion power plant. The mechanical properties of ferritic 17% Cr ODS alloys with and without the addition of Ti and Mp and 17% Cr ODS were investigated and comparison with those MA-956 alloys in the temperature range of 973K to 1573K. Nano-sized oxide dispersoids in the 17Cr-3Mo-1Ti-0.25Y_(2)O_3) alloys suppressed the grain growth during annealing at high temperature and resulted in a remarkable improvement of the high temperature strength. The oxides containing Ti was the finest and showed the most uniform dispersion.

Development of Fe-12%Cr Mechanical-Alloyed Nano-Sized ODS Heat-Resistant Ferritic Alloys

Kim, Ick-Soo,Choi, Byung-Young 대한금속학회 2002 METALS AND MATERIALS International Vol.8 No.3

The development of mechanical alloying (MA)-oxide dispersion strengthened (ODS) heat-resistant ferritic alloys of Fe-12%Cr with W, Ti and Y_2O_3 additions were carried out. Fe-12%Cr alloys with 3%W, 0.4%Ti and 0.25% Y_2O_3 additions showed a much finer and more uniform dispersion of oxide particles among the alloy system studied. Nano-sized oxides dispersed in the alloys suppress the grain growth during annealing at a high temperature and resulted in the remarkable improvement of creep strength. The oxide phase was identified as a complex oxide type of Y-Ti-O.

Ni₅Y 합금상이 형성된 Ni계 산화물 분산강화 아토마이징 분말의 밀링 거동 분석

박천웅,변종민,최원준,김영도,Park, Chun Woong,Byun, Jong Min,Choi, Won June,Kim, Young Do 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.2

Ni-based oxide dispersion strengthened (ODS) alloys have a higher usable temperature and better high-temperature mechanical properties than conventional superalloys. They are therefore being explored for applications in various fields such as those of aerospace and gas turbines. In general, ODS alloys are manufactured from alloy powders by mechanical alloying of element powders. However, our research team produces alloy powders in which the $Ni_5Y$ intermetallic phase is formed by an atomizing process. In this study, mechanical alloying was performed using a planetary mill to analyze the milling behavior of Ni-based oxide dispersions strengthened alloy powder in which the $Ni_5Y$ is the intermetallic phase. As the milling time increased, the $Ni_5Y$ intermetallic phase was refined. These results are confirmed by SEM and EPMA analysis on microstructure. In addition, it is confirmed that as the milling increased, the mechanical properties of Ni-based ODS alloy powder improve due to grain refinement by plastic deformation.

Formation of nanocrystalline MoSi₂compound subjected to mechanical alloying

Chung-Hyo Lee 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.3

Molybdenum disilicide has been recognized as an attractive candidate material for high temperature structural applications. In this study, we have used mechanical alloying by a high-energy ball milling process to produce alloy powders of α-MoSi2 starting from mixtures of elemental molybdenum and silicon powders at room temperature. The α-MoSi2 plus Mo phases have been obtained by ball milling of a Mo33Si67 mixture of the pure elements for 100 hours, which was transformed to a single α-MoSi2 phase by subsequent heat treatment up to 725 oC. The grain size of the α-MoSi2 powders thus obtained was 19 nm, being approximately four times smaller than that of commercial alloy powders. It was also seen that the α-MoSi2 phase once formed begins to transform to the high-temperature β-MoSi2 phase when the total milling time exceeds 160 hours. Molybdenum disilicide has been recognized as an attractive candidate material for high temperature structural applications. In this study, we have used mechanical alloying by a high-energy ball milling process to produce alloy powders of α-MoSi2 starting from mixtures of elemental molybdenum and silicon powders at room temperature. The α-MoSi2 plus Mo phases have been obtained by ball milling of a Mo33Si67 mixture of the pure elements for 100 hours, which was transformed to a single α-MoSi2 phase by subsequent heat treatment up to 725 oC. The grain size of the α-MoSi2 powders thus obtained was 19 nm, being approximately four times smaller than that of commercial alloy powders. It was also seen that the α-MoSi2 phase once formed begins to transform to the high-temperature β-MoSi2 phase when the total milling time exceeds 160 hours.

Alloy 617계 산화물 분산강화(ODS) 합금의 제조와 인장특성

민형기,강석훈,김태규,한창희,김도향,장진성,Min, Hyoung-Kee,Kang, Suk-Hoon,Kim, Tae-Kyu,Han, Chang-Hee,Kim, Do-Hyang,Jang, Jin-Sung 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.6

Alloy 617, Ni-22Cr-12Co-9Mo base oxide dispersion strengthened alloy was fabricated by using mechanical alloying, hot isostatic pressing and hot rolling. Uniaxial tensile tests were performed at room temperature and at $700^{\circ}C$. Compared with the conventional Alloy 617, ODS alloy showed much higher yield strength and tensile strength, but lower elongation. Fracture surfaces of the tensile tested specimens were investigated in order to find out the mechanism of fracture mode at each test temperature. Grain adjustment during tensile deformation was analyzed by electron backscattered diffraction mapping, inverse pole figures and TEM observation.

분말야금법으로 제조한 새로운 Co₁₀Fe₁₀Mn₃₅Ni₃₅Zn₁₀ 고엔트로피 합금

임다미,박형근,이병주,김형섭,Yim, Dami,Park, Hyung Keun,Tapia, Antonio Joao Seco Ferreira,Lee, Byeong-Joo,Kim, Hyoung Seop 한국분말야금학회 2018 한국분말재료학회지 (KPMI) Vol.25 No.3

In this paper, a new $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ high entropy alloy (HEA) is identified as a strong candidate for the single face-centered cubic (FCC) structure screened using the upgraded TCFE2000 thermodynamic CALPHAD database. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA is fabricated using the mechanical (MA) procedure and pressure-less sintering method. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA, which consists of elements with a large difference in melting point and atomic size, is successfully fabricated using powder metallurgy techniques. The MA behavior, microstructure, and mechanical properties of the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA are systematically studied to understand the MA behavior and develop advanced techniques for fabricating HEA products. After MA, a single FCC phase is found. After sintering at $900^{\circ}C$, the microstructure has an FCC single phase with an average grain size of $18{\mu}m$. Finally, the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA has a compressive yield strength of 302 MPa.

Ternary Cu–CNT–AlN composite coatings consolidated by cold spray deposition of mechanically alloyed powders

Pialago, Edward Joshua T.,Kwon, Oh Kyung,Kim, Min-Soo,Park, Chan Woo Elsevier 2015 Journal of Alloys and Compounds Vol.650 No.-

<P><B>Abstract</B></P> <P>Ternary copper (Cu)–carbon nanotube (CNT)–aluminum nitride (AlN) composite coatings were consolidated by the cold gas dynamic spray (CGDS) deposition of mechanically alloyed (MA) powders. The MA powder and CGDS coating samples were characterized by weight and size measurements, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The porosity and roughness of the coatings were examined by porosimetry and profilometry, respectively. Also, the wettability of the coatings in saturated liquid R134a refrigerant was investigated. The EDX analysis depicted the non-homogeneous dispersion of the AlN as well as the CNT. The XRD results revealed that the composite powders and coatings had undergone microstraining and grain size reduction due to deformation. Metallographic examination showed that the coating internal microstructures had lamellar and compacted features, which evidenced the severe deformation that resulted from the impact during particle deposition. Although the coatings had externally porous surfaces, they had dense and non-porous internal microstructures. Moreover, smaller pores were located inside the larger pores or craters on the surfaces. The addition of 10 vol.% and 20 vol.% AlN into the Cu–5CNT mixture produced ternary Cu–CNT–AlN composite coatings with fine pores that were directly open to the surfaces. Lastly, the coatings with AlN were more wettable in liquid R134a than the plain Cu plate and pure Cu and Cu–5CNT coatings.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu–CNT–AlN coatings were fabricated by mechanical alloying and cold spraying. </LI> <LI> The dispersion of fillers in the Cu–CNT–AlN coatings was not homogeneous. </LI> <LI> The Cu–CNT–AlN coatings were less rough and less porous than the other coatings. </LI> <LI> The Cu–CNT–AlN coatings had smaller surface pores than the other coatings. </LI> <LI> The Cu–CNT–AlN coatings were more wettable in liquid R134a than the other coatings. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Phase Analysis of the Mechanically Alloyed Fe-Si Powder by Differential Dissolution Technique

Kwon, Young-Soon,Kim, Hwan-Tae,Golubkova G.V.,Vlasov A.A.,Lomovsky O.I. 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.5

The binary Fe-Si elemental powders mixture (1:2 in atomic proportion) has been milled for different milling times in an attrition mill. The phase characterization of mechanically alloyed powder was investigated using the chemical method of differential dissolution (DD) and the X-ray diffraction (XRD) method. In powder specimens milled for more than 15 hr, ε-FeSi and unreacted Si were observed. The formation of a supersaturated solid solution of Si in ε-FeSi induced by mechanical alloying (MA) was also verified. The lattice parameter of the ε-FeSi of as-milled powders changed from 4.4876 Å to 4.4668 Å according to the increase of MA time. Based on the results of the DD analysis, unreacted Si could be classified as (1) crystalline Si, (2) Si supersaturated in ε-FeSi, or (3) amorphous Si. Therefore formation of the β-FeSi₂ after annealing could be explained by the reaction between the ε-FeSi and the Si classified into types (1) and (2). It seemed that the amorphous Si induced by MA did not react with the ε-FeSi during annealing at 700℃.