銅結晶における双晶形成と積層欠陥エネルギー

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  • 山本 彰利
    京都大学工学部金属加工学教室研究員，現在：川崎重工業株式会社技術研究所
  • 成田 舒孝
    京都大学工学部金属加工学教室，現在：同学部冶金学教室
  • 高村 仁一
    京都大学工学部金属加工学教室
  • 坂本 弘樹
    京都大学大学院生，現在：住友金属工業株式会社
  • 松尾 直人
    京都大学大学院生，現在：松下電器産業株式会社

書誌事項

タイトル別名
  • Stacking Fault Energy and Deformation Twinning in Copper Crystals
  • ドウ ケッショウ ニ オケル ソウショウ ケイセイ ト セキソウ ケッカン エ

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説明

The validity of our nucleation model of deformation twinning previously proposed for fcc metals has been quantitatively examined to determine the stacking fault energy γSF from the twinning stress τT, with particular attention to the orientation dependence of τT of pure copper crystals deformed in tension at 4.2 K. Main results obtained are summarized as follows:<BR>(1) τT in Cu crystals is decreased as the specimen axis approaches [111] from [100] when twinning occurs in stage III, while in stage II little affected by the orientation. This orientation dependence, consistent with that previously observed in pure Ag and Cu alloy crystals, can be quantitatively explained by our model.<BR>(2) The value of γSF of pure Cu at 4.2 K has been evaluated as 43.5±2 mJ/m2 from the twinning stress τT by using the equation derived from our model.<BR>(3) Upon nucleation of twins, the critical internal stress acting on the twinning dislocations, which arises from a dislocation pile-up in our model, is about 1.3 times as large as the applied stress in Cu crystals tested at 4.2 K. This ratio of internal stress to applied stress is the same as that previously reported in Ni-based alloys.<BR>(4) By using this stress ratio, the equation derived from our model is simplified with good approximation as γSF=ξ(R)τTbS, where ξ(R) is a parameter depending only on the specimen orientation and bS the Burgers vector of a Shockley partial dislocation.<BR>(5) This simplified formula can be applied to the case in which twinning occurs not later than early stage III where the relief of internal stress is ignored. Under this condition, the value of γSF in fcc metals and alloys is directly determined from τT in specimens oriented near [211] by a formula, γSF=2τTbS.

収録刊行物

  • 日本金属学会誌

    日本金属学会誌 47 (11), 903-911, 1983

    公益社団法人 日本金属学会

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