• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Unified Study on Brittle-Ductile Transition Based on Atomistic Point of View

Research Project

Project/Area Number 08455061
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Materials/Mechanics of materials
Research InstitutionOsaka University

Principal Investigator

KITAGAWA Hiroshi  Osaka University, Department of Mechanical Engineering, Professor, 工学部, 教授 (30029095)

Co-Investigator(Kenkyū-buntansha) OGATA Shigenobu  Osaka University, Department of Mechanical Engineering, Research Assistant, 工学部, 助手 (20273584)
NAKATANI Akihiro  Osaka University, Department of Mechanical Engineering, Associate Professor, 工学部, 助教授 (50252606)
Project Period (FY) 1996 – 1997
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 1997: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1996: ¥6,900,000 (Direct Cost: ¥6,900,000)
KeywordsMaterials Strength / Brittle-Ductile Transition / Molecular Dynamics / Atomic Force Microscope / Ceramics / Micro-Indentation / Interaction of Cracks / Grain Boundary Deformation Mechanism / 微小硬度 / ナノメカニズム / 非分離相対運動 / 転移運動 / 分子2重膜 / ミスフィット / 原子間力顕微鏡
Research Abstract

Brittle-ductile transition (BDT) was studied on the basis of atomistic pioint of view, special attention being focused on mobility of localized deformation mechanism. Main results obtained are as follows :
(1) As fracture of the material is regarded as release or relaxation process of energy which is brought from the external source, BDT is to have strong dependence on the magnitude of the energy and extend of deformed area. Concretely ;
a) Experimental results of micro-indentation test for SiC-single crystal and SiN polycrystal show that BDT appearing in highly-brittle materials seems to be a relaxation process due to mutual interaction of micro-cracks.
b) Interaction analysis between a macro crack and micro ones by homogenization method shows the stress intensity factor around the macro crack is larger than the micro, which means coalescence of the micro-cracks brings about BDT in the above case.
c) Stress shielding effect due to dislocation structure which is formed in near crack-tip field is important characteristics for BDT in ductile matallic crystal, which has been concluded after a discrete dislocation analysis.
d) From a molecular dynamics analysis of crack propagation in an amorphous metallic material, there exists no hardening mechanism of localized deformation, which in turn brittle fracture occurs macroscopically in spite of ductile rearrangement of atomic structure in micro-scale.
(2) A first-principle analysis on strength properties on Al-grain boundary indicates Si impurity decreases the strength drastically. And from same analysis for AIN-Al grain boundary, distribution of electron density indicates that physical (not chemical) property dominates in the bonding of this interface and then, fracture occurs in Al side near the boundary.

Report

(3 results)
  • 1997 Annual Research Report   Final Research Report Summary
  • 1996 Annual Research Report
  • Research Products

    (21 results)

All Other

All Publications (21 results)

  • [Publications] S.Ogata and H.Kitagawa: "Ab-initio Tensile Testing Simulation of Al, AlN and Al/AlN Composite" Advances in Materials Research. (掲載予定). (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 中谷 彰宏・北川 浩・中谷 敬子: "分子動力学法による離散転位動力学のためのせん断応力と転位運動速度の関係式の導出" 材料. 46・6. 619-124 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 中谷 彰宏・北川 浩・中谷 敬子: "分子動力学法によるbcc結晶中のモードII型き裂先端からの転位の発生と運動" 材料. 46・6. 625-630 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 中谷 彰宏: "離散転位動力学による結晶体の力学特性評価" 生産と技術. 49・3. 49-52 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 中谷 彰宏・杉崎 誠・北川 浩: "き裂先端近傍場の欠陥構造の離散転位動力学シミュレーション" 第41回日本学術会議材料研究連合講演会講演論文集. 5-6 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 北川 浩・北村 隆行・渋谷 陽二・中谷 彰宏: "初心者のための分子動力学法" 養賢堂, 146 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] H.Kitagawa: "Challenge to Mesoscopic Dynamics of Fractre" Mesoscopic Dynamics in Fracture Process (ed.H.Kitagawa, Y.Kawzoe & T.Aihara) Springer-Verlag. (in press). (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] A.Nakatani, H.Kitagawa and M.Sugizaki: "Discrete Dislocation Dynamics Stury on Distribution of Dislocation and Stress Field near Crack Tip" Mesoscopic Dynamics in Fracture Process (ed.H.Kitagawa, Y.Kawzoe & T.Aihara) Springer-Verlag. (in press). (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Ogata and H.Kitagawa: "Ab-initio Tensile Testing Simulation of Al, AlN and AL/AlN Composite" Mesoscopic Dynamics in Fracture Process (ed.H.Kitagawa, Y.Kawzoe & T.Aihara) Springer-Verlag. (in press). (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] A.Nakatani, H.Kitagawa and K.Nakatani: "Molecular Dynamics Syudy of Relationship between Shear Stress and Velocity of Dislocation for Discrete Dislocation Dynamics." J.Soc.Materials Sci.Japan. 46-6. 619-624 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] K.Nakatani, H.Kitagawa and A.Nakatani: "Molecular Dynamics Simulation on the Mechanical Strength of One-Component Amorphous Metal -Decreasing of Elastic Moduli And Strength Induced by Change of Internal Structure-" J.Soc.Materials Sci.Japan. 46-3. 244-249 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] K.Saito, H.Kitagawa , A.Nakatani and S.Ogata: "Molecular Dynamics Study on Strength of Conincidence Grain Boundaries" J.Soc.Materials Sci.Japan. 46-3. 244-249 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Ogata and H.Kitagawa: "Ab-initio Tensile Testing Simulation of Al,AlN and Al/AlN Composite" Advances in Materials Research. 掲載予定 (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] 中谷彰宏・北川 浩・中谷敬子: "分子動力法による離散転位動力学のためのせん断応力と転位運動速度の関係式の導出" 材料. 46・6. 619-624 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] 中谷彰宏・北川 浩・中谷敬子: "分子動力学法によるbcc結晶中のモードII型き裂先端からの転位の発生と運動" 材料. 46・6. 625-630 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] 中谷彰宏: "離散転位動力学による結晶体の力学特性評価" 生産と技術. 49・3. 49-52 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] 中谷彰宏・杉崎 誠・北川 浩: "き裂先端近傍場の欠陥構造の離散転位動力学シミュレーション" 第41回日本学術会議材料研究連合講演会講演論文集. 5-6 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] 北川 浩・北村隆行・渋谷陽二・中谷彰宏: "初心者のための分子動力学法" 養賢堂, 146 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] 中谷敬子 北川浩 中谷彰宏: "分子動力学法による単元系アモルファス金属の微視的空間構造と内部応力の評価" 日本機械学会論文集 A編. 62・595. 847-852 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] 中谷敬子,北川浩 中谷彰宏: "分子動力学法による単元系アモルファスの力学的性評価-原子構造変化が誘発する弾性定数および強度低下の検討" 材料. (掲載予定). (1997)

    • Related Report
      1996 Annual Research Report
  • [Publications] 尾方成信,北川浩: "第1原理分子動力学計算による窒化アルミニウム/アルミニウム界面の特性評価" 日本金属学会誌. 60・11. 1079-1083 (1996)

    • Related Report
      1996 Annual Research Report

URL: 

Published: 1996-04-01   Modified: 2016-04-21  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi