Understanding of the hardening mechanism in FCC based ordered structures induced by interstitially ordered solute atoms

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K18977
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Materials engineering and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Kimura Yoshisato 東京工業大学, 物質理工学院, 教授 (90262295)
• Research Collaborator: Murasue So ; Tsubono Yusuke ; Chai Yaw wang
• Project Period (FY): 2017-06-30 – 2019-03-31
• Keywords: 固溶強化 / 塑性変形 / 金属間化合物 / ナノインデンテーション

Outline of Final Research Achievements

Understanding of the solid solution strengthening mechanism due to interstitial elements was placed as a final goal. As the first step, E21 type intermetallic compound Ni3AlC which has an interstitial carbon atom in the octahedral interstice at the cell center was selected to investigate local elastic and plastic deformation behavior on atomistic scale using nano-indentation method while comparing with L12 type Ni3Al. So called pop-in event, discontinuous strain burst appearing on a load-penetrating depth curve corresponding to the onset of plastic deformation, was analyzed. Effect of C atoms on solid solution strengthening was found to be larger than that of Al atoms for off-stoichiometric composition on the Al-rich side. It was also indicated that C atoms might increase stress necessary to generate dislocations while they may less affect the mobility of dislocations.

Free Research Field

金属工学

Academic Significance and Societal Importance of the Research Achievements

侵入型C元素が規則固溶したE21型Ni3AlCとCo3AlCについて耐熱合金強化相としての弾塑性変形に関する知見を深め、エネルギー環境問題解決に貢献できる高性能熱電材料Half-Heusler ZrNiSnの弾塑性変形を調べて理解を進めたことには社会的に意義がある。目標に掲げた侵入型溶質原子による固溶強化の理解への道のりは険しいが、原子レベルの局所的な弾塑性変形挙動の観察および解析は塑性変形開始における転位の生成や増殖および転位の易動度を評価する上で有効であると示せたことには学術的な意義がある。今後、透過電子顕微鏡による転位の解析と組み合わせて理解をさらに深めることが期待できる。