• Title/Summary/Keyword: intermetallic

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Fraccture Behavior of Recation Squeeze Cast ($AI_20_3{\cdot}SiO_2+Ni$)/Al Hybrid Metal Matrix Composites (반응 용탕단조한(AI203 . SIO2+Ni)/Al하이브리드 금속복합재료의 파괴거동 특성)

  • 김익우;김상석;박익민
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.04a
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    • pp.67-70
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    • 2000
  • Mechanical properties of (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al hybrid composites fabricated by the reaction squeeze casting were compared with those of (15%$AI_20_3{\cdot}SiO_2$)/Al composites. Intermetallic compound formed by reaction between molten aluminum and reinforcing powder was uniformly distributed in the Al matrix. These intermetallic compounds were identified as $Al_3$NI using EDS and X-ray diffraction analysis. Microhardness and flexural strength of hybrid composites were higher than that of (15%$AI_20_3{\cdot}SiO_2$)/Al Composite. In-Situ fracture tests were Conducted on (15%$AI_20_3{\cdot}SiO_2$)/Al Composites and (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al hybrid composites to identify the microfracture process. It was identified from the in-situ fracture test of (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al composites, microcracks were initiated mainly at the short fiber / matrix interfaces. As the loading was continued, the crack propagated mainly along the separated interfacial regions and the well developed shear bands. It was identified from the in-situ fracture test of (10%$AI_20_3{\cdot}SiO_2$+5%Ni)/Al hybrid composites, microcracks were initiated mainly by the short fiber/matrix interfacial debonding. The crack proceeded mainly through the intermetallic compound clusters

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Electrochemical Corrosion Characteristics of the Intermetallic Compound NiTi from Pure Metals (금속간 화합물 NiTi와 순금속 니켈 및 티타늄의 전기화학적 부식 특성)

  • Lee, Kyu Hwan;Shin, Myung Chul
    • Analytical Science and Technology
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    • v.5 no.1
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    • pp.97-101
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    • 1992
  • Potentiodynamic corrosion tests were conducted to know the corrosion characteristics of the NiTi intermetallic compound composed of pure Ni and Ti in artificial saline. Tafel extrapolation and linear polarization technique show similar results. Corrosion current Icorr and corrosion rate was increased in the order of NiTi

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A Study on the Mechanical and Thermal Properties of Spray-cast Hypereutectic Al-Si-Fe Alloys (분사주조한 과공정 Al-Si-Fe 합금의 기계적 및 열적 특성에 관한 고찰)

  • Park, Jae-Sung;Ryou, Min;Yoon, Eui-Pak;Yoon, Woo-Young;Kim, Kwon-Hee;Kim, Myung-Ho
    • Journal of Korea Foundry Society
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    • v.26 no.3
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    • pp.123-128
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    • 2006
  • Mechanical and thermal properties of spray-cast hypereutectic Al-20wt.%Si-xwt.%Fe alloys (x=0, 1, 3, 5) were investigated. After the spray-casting, hot extrusion was performed at $400^{\circ}C$. Intermetallic compound (${\beta}-Al_5FeSi$) and primary Si are observed in the spray-cast aluminum alloys. The size of primary Si and intermetallic compound of the spray-aluminum alloys became finer and more uniformly distributed than that of the permanent mold cast ones. Ultimate tensile strength of the spray-cast aluminum alloys increased by increasing Fe contents, but that of the permanent mold cast aluminum alloys decreased by increasing Fe contents possibly due to increased amount of coarse intermatallic compound. The coefficient of thermal expansion (CTEs) of the aluminum alloys became lower with finer primary Si and intermetallic compound, and this is attributed to the increased amount of interfacial area between the aluminum matrix and the phases of finer Si and intermetallic compound.

Influence of Brazing Temperature on Strength and Structure of SUS304 Stainless Steel Brazed System with BNi-2 Filler Metal : Fundamental Study on Brazeability with Ni-Based Filler Metal(II) (BNi-2계 삽입금속에 의한 SUS304 스테인리스강 접합체의 강도와 조직에 미치는 브레이징 온도의 영향 : Ni기 삽입금속에 의한 브레이징 접합성의 기초적 검토(II))

  • Lee, Yong-Won;Kim, Jong-Hoon
    • Korean Journal of Materials Research
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    • v.17 no.3
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    • pp.179-183
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    • 2007
  • A plate heat exchanger (PHE) normally uses vacuum brazing technology for connecting plates and fins. However, the reliability of high temperature brazing, especially with nickel-based filler metals containing boron the formation of brittle intermetallic compounds (IMCs) in brazed joints is of major concern. since they considerably degrade the mechanical properties. This research was examined the vacuum brazing of commercially SUS304 stainless steel with BNi-2 (Ni-Cr-B-Si) filler metal, and discussed to determine the influence of brazing temperatures on the microstructure and mechanical strength of brazed joints. In the metallographic analysis it is observed that considerable large area of Cr-B intermetallic compound phases at the brazing layer and the brazing tensile strength is related to removal of this brittle phase greatly. The mechanical properties of brazing layer could be stabilized through increasing the brazing temperature over $100^{\circ}C$ more than melting temperature of filler metals, and diffusing enough the brittle intermetallic compound formed in the brazing layer to the base metal.

Synthesis of (Ti,Al)N Powder by the Direct Nitridation(II) (직접질화법에 의한 (Ti,Al)N계 복합질화물의 합성(II))

  • Cho, Young-Soo;Lee, Young-Ki;Sohn, Yong-Un;Park, Kyong-Ho;Kim, Seok-Yoon
    • Journal of the Korean Society for Heat Treatment
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    • v.9 no.3
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    • pp.219-227
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    • 1996
  • The purpose of this research is to develop the technology for the synthesis of (Ti,Al)N powder, which shows simultaneously the excellent properties of TiN and AlN, from the Ti-Al intermetallic compounds by the direct nitriding method. The effects of variables such as temperature, Ti-Al intermetallic compounds ($TiAl_3$, TiAl and $Ti_3Al$) were investigated by TG, XRD and SEM. The (Ti,Al)N powder can be easily synthesized from the intermetallic compounds by the direct nitriding method. Among the intermetallic compounds, the nitriding behavior increased with TiAl> $Ti_3Al$ > $TiAl_3$, as the difference of diffusion coefficient for nitrogen in each materials. The ternary nitride such as $Ti_2AlN$ and $Ti_3Al_2N_2$ can be synthesized by the direct nitriding method, although the ternary nitride coexist with TiN and AlN. The ternary nitrides are stable below $1400^{\circ}C$, but these are gradually decomposed into TiN and AlN above $1400^{\circ}C$.

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Computational Study of Intermetallic Reaction Propagation in Nanoscale Boron/Titanium Metallic Multilayers (보론/티타늄 나노박막다층 내 이종금속간 화학반응 전파특성 해석연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.3
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    • pp.10-17
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    • 2017
  • The analytical modeling has been established on the self-propagation of intermetallic reaction in the spanwise direction of highly reactive boron and titanium nanoscale multilayers. Assuming that the reaction obeys Arrhenius kinetics, two-dimensional computations are carried out for heat and atomic species diffusion with exothermic reaction model in order to simulate the self-propagation of intermetallic reaction. The effects of bimetallic layer thickness and thickness ratio on the reaction propagation speed are tested and discussed in addition to the assessment of pre-mixing zone effects.

Formation of a V-Added Ti Aluminide Multilayered Sheet by Self-Propagating High-Temperature Synthesis and Diffusion Annealing (고온자전합성과 확산 열처리를 이용한 V 이 첨가된 TiAl계 금속간화합물 복합판재의 제조)

  • Kim, Yeon-Wook
    • Korean Journal of Materials Research
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    • v.12 no.9
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    • pp.696-700
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    • 2002
  • The Ti-aluminide intermetallic compound was formed from high purity elemental Ti and Al foils by self-propagating, high-temperature synthesis(SHS) in hot press. formation of $TiAl_3$ at the interface between Ti and Al foils was controlled by temperature, pressure, heating rate, and so on. According to the thermal analysis, it is known in this study that the heating rate is the most important factor to form the intermetallic compound by this SHS reaction. The V layer addition between Al and Ti foils increased SHS reaction temperatures. The fully dense, well-boned inter-metallic composite($TiA1/Ti_3$Al) sheets of 700 m thickness were formed by heat treatment at $1000^{\circ}C$ for 10 hours after the SHS reaction of alternatively layered 10 Ti and 9 Al foils with the V coating layer. The phases and microstructures of intermetallic composite sheets were confirmed by EPMA and XRD.

The Observation of Intermetallic Compound Microstructure Under Sn Whisker in Lead-free Finish

  • Yu, Chong-Hee
    • Journal of the Microelectronics and Packaging Society
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    • v.16 no.2
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    • pp.27-31
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    • 2009
  • Sn whiskers can grow from the pure Sn and high Sn-based finish and cause the electrical shorts and failures. Even with the wealth of information on whiskers, we have neither the clear understanding of whisker growth nor methods for its prevention. In this study, the whisker grain roots which connected with intermetallic layer were analyzed by high-resolution transmission electron microscopy (HR-TEM). In the Sn-Cu plated leadframe (LF) that was stored at ambient condition for 540 days, filament-shaped whiskers were grown on the Sn-plated surface and ${\eta}'-Cu_6Sn_5$ precipitates were widely distributed along the grain boundaries at the Sn matrix. The measured of the lattice fringes at the ${\eta}'-Cu_6Sn_5$ was $4.71{\AA}$ at the coarse grain and $2.91{\AA}$ at the fine grain. The $Cu_3Sn$ which generates the tensile stresses was not observed. The formation of $Cu_6Sn_5$ precipitates and intermetallic layer were strongly related to whisker growth, but, the whisker growth tendency does not closely relate with the geometric morphology of irregularly grown intermetallic compound (lMC).

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Analysis on Milling Behavior of Oxide Dispersion Strengthened Ni-based Atomizing Powder with Ni5Y Intermetallic Phase (Ni5Y 합금상이 형성된 Ni계 산화물 분산강화 아토마이징 분말의 밀링 거동 분석)

  • Park, Chun Woong;Byun, Jong Min;Choi, Won June;Kim, Young Do
    • Journal of Powder Materials
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    • v.26 no.2
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    • pp.101-106
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    • 2019
  • 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.

The corrosion of aluminium alloy and release of intermetallic particles in nuclear reactor emergency core coolant: Implications for clogging of sump strainers

  • Huang, Junlin;Lister, Derek;Uchida, Shunsuke;Liu, Lihui
    • Nuclear Engineering and Technology
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    • v.51 no.5
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    • pp.1345-1354
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    • 2019
  • Clogging of sump strainers that filter the recirculation water in containment after a loss-of-coolant accident (LOCA) seriously impedes the continued cooling of nuclear reactor cores. In experiments examining the corrosion of aluminium alloy 6061, a common material in containment equipment, in borated solutions simulating the water chemistry of sump water after a LOCA, we found that Fe-bearing intermetallic particles, which were initially buried in the Al matrix, were progressively exposed as corrosion continued. Their cathodic nature $vis-{\grave{a}}-vis$ the Al matrix provoked continuous trenching around them until they were finally released into the test solution. Such particles released from Al alloy components in a reactor containment after a LOCA will be transported to the sump entrance with the recirculation flow and trapped by the debris bed that typically forms on the strainer surface, potentially aggravating strainer clogging. These Fe-bearing intermetallic particles, many of which had a rod or thin strip-like geometry, were identified to be mainly the cubic phase ${\alpha}_c-Al(Fe,Mn)Si$ with an average size of about $2.15{\mu}m$; 11.5 g of particles with a volume of about $3.2cm^3$ would be released with the dissolution of every 1 kg 6061 aluminium alloy.