Evaluation of auxetic property in metallic alloy

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K22037
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 26:Materials engineering and related fields
• Research Institution: Tohoku University
• Principal Investigator: KAINUMA Ryosuke 東北大学, 工学研究科, 教授 (20202004)
• Project Period (FY): 2019-06-28 – 2021-03-31
• Keywords: CuAlMn系合金 / オーセチック特性 / 形状記憶特性 / 異常粒成長 / 単結晶

Outline of Final Research Achievements

According to some theoretical studies, auxetic property, i.e., negative Poisson’s ratio, is predicted in many bcc-based Intermetallic Compounds (IMCs). In the present study, some CuAlMn single crystals obtained by cyclic heat treatment from LD<110> texture samples were investigated to prove the peculiar property.
By application of tensile stress to LD[110], the negative Poisson’s ratio was confirmed in [1-10] direction, which was consistent with the theoretical results predicted with the moduli experimentally obtained. Furthermore, in [001] direction, a large Poisson’s ratio over 1.0 was detected. These properties were also obtained in the {001}<110> textured polycrystalline sample fabricated by cold rolling and annealing. This means that the properties are available to functional devices such as mechanical diode.

Free Research Field

工学

Academic Significance and Societal Importance of the Research Achievements

従来、FeGa以外では実証されていなかった規則bcc金属間化合物（IMC）に出現する負のポアソン比について、CuAlMnにおいてもLD<110>に対しTD＜1-10＞方向において理論通り生じることを証明し、その起源は弾性定数C’が異常に小さいことにあることを示した。以上の結果から、他の規則bcc-IMCにおおても同様の現象が得られる可能性が十分にあることを示した。また、本現象は単結晶だけでなく多結晶でも得られることから、差し込むことで抜くことが難しい機械ダイオードといった機能性部材への応用が期待できる。