Bonding mechanism and interfacial microstructure evolution in explosively welded hard-to-weld light materials

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14425
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Mihara-Narita Mami 名古屋工業大学, 工学(系)研究科(研究院), 助教 (40886727)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 爆発圧着法 / マグネシウム合金 / アルミニウム合金 / 異種金属接合

Outline of Final Research Achievements

In this study, the effectiveness of the explosive welding method was evaluated for joining magnesium alloys and aluminum alloys, which are difficult-to-weld materials. The brittle intermetallic compound, which is a problem when joining the two alloys, formed very thin (less than 1 μm) at the interface, and its thickness depended on the aluminum concentration in the magnesium alloy. The annealing treatment after welding increased the thickness of the interlayer at the bonding interface and decreased the bond strength. It was found that brittle β-Al3Mg2 phase formed at the bonding interface after annealing, which reduced the bond strength. The residual stress state at the bonding interface was tensile on the magnesium alloy side and compressive on the aluminum alloy side, and the residual stress decreased with increasing annealing time.

Free Research Field

材料組織制御

Academic Significance and Societal Importance of the Research Achievements

本研究は，車体重量を抜本的に軽量化する新規材料として期待されるマグネシウム合金を，軽量材料として広く用いられるアルミニウム合金と組合せ，適材適所に取り入れることを目指すものである。両合金は難溶接材であり，これを克服するために爆発圧着（爆着）法を適用した。本研究成果において，接合界面における中間層の形成を抑えた高い接合強度を持つ接合体が得られた。従来の接合手法では接合界面に形成する中間層を1μm以下の厚みに制御することが困難であり，爆着法の有用性を明らかにできた。また，中間層の生成機構について明らかにした点も，学術的に意義の高い研究である。