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Formation Mechanism of Fracture Precursor Induced by Phase Transformation in beta Type Ti-Mo Alloy

Research Project

Project/Area Number 07650769
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Physical properties of metals
Research InstitutionOkayama University

Principal Investigator

HIDA Moritaka  Okayama University・Faculty of Engineering, Professor, 工学部, 教授 (90023134)

Co-Investigator(Kenkyū-buntansha) TAKEMOTO Yoshito  Okayama University・Faculty of Engineering, Assistant Professor, 工学部, 助手 (60216942)
SAKAKIBARA Akira  Okayama University・Faculty of Engineering, Associate Professor, 工学部, 助教授 (40033245)
Project Period (FY) 1995 – 1996
Project Status Completed (Fiscal Year 1996)
Budget Amount *help
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1996: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1995: ¥2,100,000 (Direct Cost: ¥2,100,000)
Keywordstitanium molybdenum alloy / titanium nickel shape memory alloy / omega transformation / alpha transformation / martensitic transformation / {332} <113> twin / transition state / electron microscopy / チタン-モリブデン合金 / {332}〈113〉双晶 / オメガ相変態 / 透過電顕観察 / 逆変態 / 変形帯 / 加工軟化 / 破壊前駆現象 / 不連続変形
Research Abstract

This study has been carried out mainly by electron microscopic observation. The summary is as follows :
1. It is well known that hardening and embrittlement of beta type Ti-14Mo alloy are caused by aged (1) -phase formation. According to the study on deformation bands formed during tensile test at the aging temperature, the reverse transformation ((1) *beta) in the band drove preferential plastic deformation (work softening) in the band. This was recognized as an origin of the inacroscopic embrittlement. It was also newly observed that the hardness of over-aged alloy decreased without changing (1) -particle size and brittleness. The transition state, (1) *alpha, prepared by a step-aging made the alloy ductile emitting bundles of needle -like alpha-phase into matrix during tensile deformation. The ductility was better than that of the alloy with large alpha-phase formed by direct aging.
2. It is well known that the as-quenched alloys show remarkable ductility with {332} twinning. The twinning mechanism which had not been cleared was determined by a model simulation of atom displacements to {332} twin from bee structure via alpha" martensitic transformation. Cutting and interaction between {332} twins maybe give rise to the local deformation at a kind of fractural precursors which are expected to be planar (1) -phase. The identification with TEM is now in progress.
3. In-situ observation on Ti-50.6% Ni shape memory alloy revealed that the deformation in plastic region multiplied the secondary martensitic plates between and/or from the primary ones which were formed during quasi-elastic deformation. Cutting and interaction between the plates led the sample to fracture.
4. Several cluster models of a given structure (beta, (1), alpha or alpha") were studied with DX-Xalpha method. The bond orders obtained seems to be effective in comparing the strength of stress induced products which stimulate work softening.

Report

(3 results)
  • 1996 Annual Research Report   Final Research Report Summary
  • 1995 Annual Research Report
  • Research Products

    (11 results)

All Other

All Publications (11 results)

  • [Publications] 蒋,飛田,竹元,榊原,藤井: "TiNi形状記憶合金の局所変形におよぼす相変態の影響" 材料. 45・4. 411-416 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 竹元,飛田,榊原: "β型Ti-Mo合金のマルテンサイト型{332}<113>双晶" 日本金属学会誌.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 竹元,飛田,榊原: "Precursive Transformation before Brittle Fracture in Aged Ti-Mo Alloy" Proceedings 8th World Conference on Titaniumn. 3. 2296-2302 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 蒋,飛田,竹元,榊原,保田,森: "In Situ Observation of Stren Induced Martensitic Transformation and Plactic Deformation in TiNi Alloyn" (発表予定).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] X.Jiang, M.Hida, Y.Takemoto, A.Sakakibaa and S.Fujii: "Effect of Phase Transformation on Localized Deformation in Ti-Ni Shape Memory Alloy" Journal of the Society of Materials Science Japan. 45-4. 411-416 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Y.Takemoto, M.Hida and A.Sakakibara: "Martensitic {332} <113> Twinin beta Type Ti-Mo Alloy" Journal of Japan Institute of Metals. 60-11. 1072-1078 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Y.Takemoto, M.Hida and A.Sakakibara: "Precursive Transformation before Brittle Fracture in Aged Ti-Mo Alloy" Proceedings of the 8th World Conference on Titanium. vol.3. 2296-2302 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] X.Jiang, M.Hida, Y.Takemoto, A.Sakakibara, H.Yasuda and H.Mori: "In Situ Observation of Stress Induced Martensitic Transformation and Plastic Deformation in TiNi Alloy" (to be published).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 蒋,飛田,竹元,榊原,藤井: "TiNi形状記憶合金の局所変形に及ぼす相変態の影響" 材料. 45・4. 411-416 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] 竹元,飛田,榊原: "β型Ti-Mo合金のマルテンサイト型{332}〈113〉双晶" 日本金属学会誌. 60・11. 1072-1078 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Yoshito Takemoto: "Nature of Brittle Fracture in Aged Ti-Mo Alloy" Memoirs of the Faculty of Engineering,Okayama University. 30. 1-7 (1996)

    • Related Report
      1995 Annual Research Report

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Published: 1995-04-01   Modified: 2016-04-21  

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