Explication of the mechanism of superplasticity of Sn-Bi based alloys

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03859
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Gunma National College of Technology
• Principal Investigator: Yamauchi Akira 群馬工業高等専門学校, 機械工学科, 准教授 (60396520)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: Sn-Bi合金 / 超塑性 / 鉛フリーはんだ / 接合 / 低融点

Outline of Final Research Achievements

The purpose of this study is to clarify the conditions and mechanism of superplasticity in the Sn-Bi based alloys in order to improve the ductility of Sn-Bi based alloys.
These experimental results was found that the improvement of the ductility of Sn-Bi based alloys in the addition of Cu, Ni, Sb, Zn. It was found the superplastic behavior at high temperature (more than 333 K) and low strain rates (under 5.25×10-4 s-1). From the results of the microstructure observation after superplasticity, it was observed that the primary crystal Sn grains could not deform along the axial direction. Consequently, the eutectic microstructure contributed to the superplastic deformation of Sn-Bi based alloys.

Free Research Field

機械材料

Academic Significance and Societal Importance of the Research Achievements

本研究成果は、Sn-Bi合金の変形挙動を力学的・金属組織学的に調査することにより、添加元素の影響を材料学的に明らかにした。また、Sn基合金の超塑性変形挙動については報告されていたものの、そのメカニズムについてはこれまで不明であったが、本研究成果により初めてSn-Bi合金の超塑性変形メカニズムを明らかにしたことは学術的に高い意義を持つ。
このような変形機構により低温接合技術は汎用的に使用される可能性が広がり、その接合体の長寿命化も期待されることから、今後の実装技術の発展などによる社会的意義が高く、実装分野における貢献度も高い。