超塑性・ナノクリスタルの疲労

• Material Type: 文書・図像類
• Title: 超塑性・ナノクリスタルの疲労
• Author/Editor: VINOGRADOV, Alexey
• Author Heading: VINOGRADOV, Alexey
• Publication Date: 1999-12-07
• Publication Date (W3CDTF): 1999-12-07
• Alternative Title: Fatigue of Superplastic-Nanocrystals
• Periodical title: 平成10(1998)年度 科学研究費補助金 基盤研究(C) 研究成果報告書概要 = 1998 Fiscal Year Final Research Report Summary
• No. or year of volume/issue: 1997 – 1998
• Volume: 1997 – 1998
• Pages: 3p.-
• Text Language Code: jpn
• Subject Heading: 超微細結晶材料; UFG; 超塑性; 疲労; 繰返し変形; Ultrafine Grained Material; Superplasticity; Fatigue; Cyclic Deformation
• Target Audience: 一般
• Note (General): 金沢大学工学部; 本研究課題では,室温において超塑性変形をしめす超微細結晶材料の疲労変形機構を明らかにすることを最終的な目標として,(1)単結晶材料,(2)Equal Channel Angular Extrusion(ECAE)加工された超微細結晶粒銅,および(3)EACE加工されたPb-62%SnとZn2-2%Al合金の繰返し応力-ひずみ応答を調査した.銅,Fe-Cr,Fe-Cr-Niなどの単結晶や三重結晶を用いて結晶性材料の繰返し応答の基礎的な特徴を調査した.単結晶材料では特定の塑性ひずみ振幅域において固執すべり帯(PSB)が形成され,その形成にともなってバウシンガ効果が大きく変化することが明らかになった.また三重結晶を用いた研究では,結晶間の残留応力がバウシンガ効果の原因の一つであることを実験的に示した.ナノクリスタルの繰返し変形の基礎的側面を調査するために行った超微細結晶粒銅の繰返し変形試験では以下のようなことが明らかになった.ECAE加工された銅の応力振幅は250MPaにも到達し,バウシンガ効果も非常に高かった.しかしながら,微細結晶粒銅のそれらの特性は200℃程度の熱処理で劇的に変化した.ECAE加工されたPb-SnおよびZn-Al合金では,室温においても大きな伸びと流動応力の大きなひずみ速度依存性が一方向変形において観察された.繰返し変形試験では,初期段階から応力振幅は飽和状態に達した.Zn-Al合金では飽和応力振幅およびバウシンガ効果はひずみ速度が増加するにつれて増加した.一方,一方向変形おいて流動応力のひずみ速度依存性が特に大きかったPb-Sn合金では逆に応力振幅およびバウシンガ効果にひずみ速度依存性はほとんど見られず,一方向変形とは異なる傾向を示した.応力振幅およびバウシンガ効果の繰返し変形でみられたひずみ速度依存性は,Pb-Snでは超塑性変形に必要な熱活性化過程が作用しないこと,Zn-Alでは転位密度が増加することからそれぞれ理解することは可能であった.; In order to investigate fatigue mechanisms of ultrafine grained materials showing superplasticity at room temperature, we have examined cyclic stress-strain response of (1) single crystal specimens, (2) ultrafine grained copper produced by "Equal Channel Angular Extrusion (ECAE)" method, and (3) Pb-62%Sn and Zn-22%AI alloy fine-grained by the ECAE method.Fundamental aspects of the cyclic response in crystalline materials were investigated in single- and tr-crystal specimens of copper, Fe-Cr alloy and Fe-Ni-Cr alloy. The single crystal experiments revealed that fatigue deformation gives rise to formations of "persistent slip bands" (PSBs) at a certain range of plastic strain amplitude. The formation of the PSBs induced a drastic changes in Bauschinger energy parameter. In the fatigue tests on the tricrystal specimens, it was experimentally shown that residual stresses between adjoining grains is one-of sources for the Bauschinger effect in the crystalline materials.in the cyclic deformation tests on ultrafine grained copper to characterize basic feature of fatigued nano-crystals, following results were obtained. The stress amplitude of the copper fined-grained by the ECAE method became up to 250 MPa. The Bauschinger effect was also significantly high. However, this kind of excellent property of the ultrafine grained copper was very sensitive to heat treatment : both the Stress amplitude and the Bauschinger effect were apparently reduced by an annealing at 200ﾟC.In the monotonic tensile tests, both the Pb-Sn and Zn-Al specimens showed large elongations even at room temperature. These two materials also showed significant strain-rate dependence of flow stress. In the cyclic deformation tests, the stress amplitudes in the Pb-Sn and Zn-Al alloys were almost saturated from the beginning of the experiments, although a cyclic hardening curve of the annealed copper was divided clearly into the hardening and saturation stages. The stress amplitude and the Bauschinger effect in the Zn-Al alloy apparently increased with increasing strain rate. On the other hand, the Pb-Sn alloy revealed no strain rate dependence of the stress amplitude and the Bauschinger effect. This tendency obtained in the cyclically deformed Pb-Sn alloy is completely different from the result in the monotonic- test. (The cyclic response of the annealed copper was -. independent of the strain rate as well as the yield stress under monotonic deformation.) The absence of the strain-rate dependence in the cyclically deformed Pb-Sn alloy can be attributed to the missing of thermally activated processes which are dominant in the monotonic deformation : the applied plastic strain was probably accommodated substantially by dislocation motion because the plastic strain amplitude is very low with compared to the monotonic deformation. On the other hand, the cyclic deformation in the Zn-Al alloy may involve the thermally activated processes such as dislocation climb and grain boundary diffusion. It is feasible that the plastic strain can not be accommodated only by the dislocation motion because the grain size of the Zn-Al was very small.; 研究課題/領域番号:09650715, 研究期間(年度):1997 – 1998; 出典：研究課題「超塑性・ナノクリスタルの疲労 」課題番号09650715（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/report/KAKENHI-PROJECT-09650715/096507151998kenkyu_seika_hokoku_gaiyo/）を加工して作成
• DOI: 10.24517/00066006
• Access Restrictions: 限定公開
• Related Material: https://kaken.nii.ac.jp/search/?qm=10283102; https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650715/; https://kaken.nii.ac.jp/ja/report/KAKENHI-PROJECT-09650715/096507151998kenkyu_seika_hokoku_gaiyo/
• Data Provider (Database): 国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）; https://irdb.nii.ac.jp
• Original Data Provider (Database): 金沢大学 : 金沢大学学術情報リポジトリKURA