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STRESS RELAXATION IN MULTIPHASE SYSTEMS : MICROMECHANICAL STUDY OF THE EFFECTS OF DIFFUSION AND VISCOUS SLIDING AT PHASE INTERFACES

Research Project

Project/Area Number 10450256
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Structural/Functional materials
Research InstitutionTokyo Institute of Technology

Principal Investigator

WAKASHIMA Kenji  Precision and Intelligence Laboratory, Tokyo Institute of Technology, Professor, 精密工学研究所, 教授 (70016799)

Project Period (FY) 1998 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥9,600,000 (Direct Cost: ¥9,600,000)
Fiscal Year 1999: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1998: ¥7,100,000 (Direct Cost: ¥7,100,000)
KeywordsComposite Materials / Creep / Stress Relaxation / Interfacial Diffusion / Viscous Sliding / Micromechanics / Internal Stress / Metal Matrix Composites / 界面すべり / 金属基複合材料
Research Abstract

Theoretical and experimental work has been done in this project with a primary objective to indicate a new route to the understanding of high-temperature deformation behavior (creep) of metal-matrix composites (MMCs) with ceramic reinforcements--a class of light-weight high-stiffness 'advanced materials' currently ranked above conventional metallic materials especially for use in elevated temperature environment. Emphasis is placed on the viscous nature of metal-ceramic phase interfaces which causes 'stress relaxation' and hence plays a substantial role in creep of MMCs. First, as basic preliminaries to our intention, a series of analysis based on 2-D and 3-D continuum models has been made to formulate a micromechanical description of creep in two-phase (or multi-phase) solid systems wherein both diffusional mass flow and viscous sliding occur along phase interfaces. This description is applied to diffusional creep in polycrystals, leading us to make comments on existing theories where … More in the role of boundary sliding is entirely ignored. It is found that such theories can be justified only if boundary viscosity is so small that sliding can occur instantaneously. Further effort is devoted exclusively to our primary objective, giving special attention to particulate SiC-reinforced aluminum-based MMCs produced by powder-metallurgy processing routes. To begin with, 'anelastic relaxation' caused by diffusional creep around ceramic particulates is addressed. A micromechanical model of the relaxation has been presented and its validity confirmed from measurements of dynamic Young's modulus and internal friction, each as a function of temperature, in low-amplitude low-frequency conditions of cyclic uniaxial loading. The model is then extended into the high-stress 'dislocation creep' regime for the matrix, i.e. the case where the matrix itself does not remain elastic but creeps according to the 'power law.' With attention confined to the 'class I creep behavior' characterized by the particular stress exponent n = 3, nonlinear unsteady creep behavior of MMCs has been formulated in an entirely analytical manner. This formulation allows us to gain new insight into a 'puzzle' as to the anomalously high apparent stress exponents in 'minimum creep rate' data for MMCs. The crux of the matter consists in that damage processes (particle cracking and interface debonding) very likely occur in creep at high stresses and hence not all the minimum creep rate data should be interpreted as representatives of the steady state. This has been substantiated by carefully designed experiments on a particulate SIC/6061 A1 MMC. Less

Report

(3 results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report
  • Research Products

    (20 results)

All Other

All Publications (20 results)

  • [Publications] C.-S. Kang: "Dynamic Young's modulus and internal friction in particulate Sic/Al composites"Acta Materialia. 46. 1209-1220 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Onaka: "Kinetics of stress relaxation caused by the combination of interfacial sliding and diffusion : two-dimensional analysis"Acta Materialia. 46. 3821-3828 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T. Mori: "Role of grain-boundary sliding in diffusional creep of polycrystals"Journal of Applied Physics. 83. 7547-7552 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T. Mori: "Steady-state creep of a composite analyzed by an energy balance method"Philosophical Magazine Letters. 78. 331-338 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Onaka: "Stress relaxation caused by the combination of interfacial sliding and diffusion around spherical inclusions"Mechanics of Materials. 31. 717-727 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] K. Wakashima: "Steady-state creep of a particulate Sic/6061 Al composite"Acta Materialia. 48. 891-901 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] K. Wakashima: "Back-stress evolution during creep of a metal matrix composite : an analysis by the mean-fied approach and its implications"Materials Science and Engineering, A. (印刷中). (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] C. -S. Kang: "Dynamic Young's modulus and internal friction in particulate SiC/Al composites"Acta Materialia. 46. 1209-1220 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Onaka: "Kinetics of stress relaxation caused by the combination of interfacial sliding and diffusion : two-dimensional analysis"Acta Materialia. 46. 3821-3828 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T. Mori: "Role of grain-boundary sliding in diffusional creep of polycrystals"Journal of Applied Physics. 83. 7547-7552 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] T. Mori: "Steady-state creep of a composite analyzed by an energy balance method"Philosophical Magazine Letters. 78. 331-338 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] S. Onaka: "Stress relaxation caused by the combination of interfacial sliding and diffusion around spherical inclusions"Mechanics of Materials. 31. 717-727 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] K. Wakashima: "Steady-state creep of a particulate SiC/6061 Al composite"Acta Materialia. 48. 891-901 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] K. Wakashima: "Back-stress evolution during creep of a metal matrix composite: an analysis by the mean-fied approach and its implications"Materials Science and Engineering, A. (in press).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] K.Wakashima: "Steady-State Creep of a Particulate SiC/6061 Al Composite"Acta Materialia. 48・4. 891-901 (2000)

    • Related Report
      1999 Annual Research Report
  • [Publications] S.Onaka: "Stress Relaxation,Caused by the Combination of Interfacial Sliding and Diffusion around Spherical Inclusions"Mechanics of Materials. 31. 717-727 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] K.Wakashima: "Back Stress Evolution during Creep of a Metal Matrix Composite : An Analysis by the Mean-Field Model" Materials Science and Engineering,A. (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] T.Mori: "Steady-State Creep of a Composite Analyzed by an Energy Balance Method" Philosophical Magazine Letters. 78・5. 331-338 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] S.Onaka: "Kinetics of Stress Relaxation Caused by the Combination of Interfacial Sliding and Diffusion : Two Dimensional Analysis" Acta Materialia. 46・11. 3821-3828 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] T.Mori: "Role of Grain-Boundary Sliding in Diffusional Creep of Polycrystals" Journal of Applied Physics. 83・12. 7547-7552 (1998)

    • Related Report
      1998 Annual Research Report

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Published: 1998-04-01   Modified: 2016-04-21  

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