Development of high-performance single crystal shape memory alloy sheet by controlling crystallographic orientation

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05175
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: Iwate University (2022); Japan Aerospace EXploration Agency (2020-2021)
• Principal Investigator: Tobe Hirobumi 岩手大学, 理工学部, 准教授 (40743886)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: Cu-Al-Mn合金 / 形状記憶合金 / 集合組織 / マルテンサイト変態 / 再結晶

Outline of Final Research Achievements

The objective of this study is to establish a method to control the crystallographic orientation of β phase (bcc structure), which exhibits shape memory properties in Cu-Al-Mn shape memory alloys, and to enable a stable supply of alloy sheets with excellent properties. By repeating a combined process of forming fine α phase (fcc structure) by specific heat treatment and cold rolling, we have developed a sheet material whose crystal orientation is aligned around <510>, where the recovery strain is maximum. Even if polycrystalline or single crystalline β-phase is obtained by subsequent heat treatment, the favorable orientation is inherited, and thus sheets with excellent shape memory properties exhibiting large recovery strain can be obtained with high frequency.

Free Research Field

材料加工・組織制御

Academic Significance and Societal Importance of the Research Achievements

熱処理による単結晶化手法は、Cu-Al-Mn形状記憶合金に優れた形状記憶特性をもたらすが、これまでの手法では結晶方位にばらつきがあり、製造した単結晶板材の特性にばらつきが生じるという課題があった。本研究で開発した結晶方位制御手法は、既存の単結晶化手法と組み合わせることでこのばらつきを低減でき、安定した特性を有する板材を供給可能とする。このような形状記憶合金板材は、温度変化で変位や力の発生をもたらす熱的駆動アクチュエータとして利用でき、例えば宇宙機温度制御用ヒートスイッチ等の性能向上・品質改善に貢献できる。