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Athermal Bubble-Strengthening at High Temperatures in P/M Tungsten Fine Wires

Research Project

Project/Area Number 09650766
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Structural/Functional materials
Research InstitutionKYUSHU INSTITUTE OF TECHNOLOGY

Principal Investigator

TANOUE Koji  Kyushu Institute of Technology, Department of Materials Science of Technology, Associate Professor, 工学部, 助教授 (80039122)

Project Period (FY) 1997 – 1998
Project Status Completed (Fiscal Year 1998)
Budget Amount *help
¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1998: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywordsbubble / interlocking / non-sag grain structure / creep / high temperature / deformation mechanism map / filament / secondary recrystallized grain / 粒界破壊
Research Abstract

Scanning electron microscopic (SEM) observation is made to examine the geometry of bubbles in P/H tungsten fine wires after their secondary recrys-tallization is completed. While bubbles, the mean diameter of which is 23 nm, are present at grain boundaries with a high area density of p =10^<13> m^<-2>, the area density of bubbles inside a grain is about 5 % of p . It is also investigated how the morphological change of secondary recrystallized grains grown in tungsten fine wires has an effect on creep at high temperatures after it is quantitatively estimated. The quantitative treatment of the grain morphology is possible by using f1 as the representative one of the grain shape parameters. The optimum interlocked grain structure is defined as the grain morphology in which the grain aspect ratio is minimized under the condition that the area of grain boundaries does not increase drastically. The high-temperature creep can then be characterized by the index DELTA I(=f1-f1^O) which indicat … More es the degree of deviation from the optimum interlocking of grains which is designated by f1^0. The region of power law creep in the deformation mechanism maps is minimized at DELTA I=0 at which the grains are most favourably interlocked, being extended as DELTA I deviates from DELTA 1=0. It is considered that the deformation in the region is strongly influenced by grain boundary sliding, being further done by grain boundary cavitation with an increase in DELTA I at DELTA 1>0.
These results have been published in the journals which are listed in another sheet. Many arrays of bubbles existing in wire play an important role in controlling the morphology of secondary recrystallized grains. It was proved that the high-temperature strength is strongly influenced by the grain morphology which is determined by the distribution of bubbles. Accordingly, the athermal bubbles-strengthening is obscured by the change of the grain morphology. It is under consideration how to estimate the net effect of the athermal bubbles-strengthening on the flow stress. Less

Report

(3 results)
  • 1998 Annual Research Report   Final Research Report Summary
  • 1997 Annual Research Report
  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] Koji Tanoue: "Grain Shape Parameters for High-Temperature Creep Resistance in Powder Metallurgy Tungsten Fine Wires" Metallurgical and Materials Transactions A. 29A・2. 519-526 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Koji Tanoue: "Morphological Effect of Grains on Deformation Mechanism Maps of P/M Tungsten Fine Wires" Proceedings of 1998 Powder Metallurgy World Congress & Exhibition. Vol.4. 492-497 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 田上耕司、緒方博之: "焼結タングステン細線の高温クリープに及ぼす2次再結晶粒形態の影響" 日本金属学会誌. 63・5(掲載予定). (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Koji Tanoue: "Grain Shape Parameters for High-Temperature Creep Resistance in Powder Metallurgy Tungsten Fine Wires" Metallurgical and Materials Transactions A. Vol.29A. 519 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Koji Tanoue: "Morphological Effect of Grains on Deformation Mechanism Maps of P/M Tungsten Fine Wires" Proceedings of the 1998 Powder Metallurgy World Congress & Exhibition. 492 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] K.Tanoue and H.Ogata: "Morphological Effect of Secondary Recrystallized Grains on High-Temperature Creep of P/M Tungsten Fine Wires" To be published in J.Japan Inst.Metals. Vol.63. (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] Koji Tanoue: "Grain Shape Parameters for High-Temperature Creep Resistance in Powder Metallurgy Tungsten Fine Wires" Metallurgical and Materials Transactions A. 29A・2. 519-526 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] Koji Tanoue: "Morphological Effect of Grains on Deformation Mechanism Maps of P/M Tungsten Fine Wires" Proceedings of 1998 Powder Metallurgy World Congress & Exhibition. Vol.4. 492-497 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] 田上耕司、緒方博之: "焼結タングステン細線の高温クリープに及ぼす2次再結晶粒形態の影響" 日本金属学会誌. 63・5(掲載予定). (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] 田上耕司、向山慶彦: "焼結タングステン細線中のバブルの幾何学的特性とその異常結晶粒成長に及ぼす影響に関する計算機実験" 日本金属学会誌. 61・11. 1188-1197 (1997)

    • Related Report
      1997 Annual Research Report

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Published: 1997-04-01   Modified: 2016-04-21  

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