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Chihiro Iwamoto
Department of Materials Science and Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511, Japan

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Journal article
Published: 08 May 2019 in Metals
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The effect of Cu coating metallic interlayer on the weldability, joint strength, and interfacial microstructure during high-power ultrasonic spot welding (HP-USW) of AZ31B Mg alloy has been studied. Interlayered samples exhibited good weldability and they resulted in strong sound joints with nearly the same strength as joints without interlayer, with the distinction of lower energy being required. The Cu interlayer affected the thermal and vibrational properties of the interface, as the maximum interface temperature decreased and approached better uniformity across the weld nugget. The base metal grain structure changed to equiaxed larger grains after ultrasonic welding and a chain of parent metal small grains were observed around the interface. A binary intermetallic compound product of Mg-Cu, which was rich in Mg, has been found around the interface that was diffused toward base metal. According to the electron probe micro-analyzer (EPMA) results, alongside temperature measurements and hardness data, the formation of Mg2Cu is suggested in this region. At the interface centerline, a narrow region was identified that was composed of Mg, Cu, and Al. Complementary transmission electron microscopy analysis estimated that Al-containing reaction product is a ternary alloy of the MgCuxAly type. The dispersion of fine grain intermetallic compounds as discrete particles inside Mg substrate in both interfacial regions formed a composite like structure that could participate in joint strengthening.

ACS Style

Amir Badamian; Chihiro Iwamoto; Shigeo Sato; Suguru Tashiro. Interface Characterization of Ultrasonic Spot-Welded Mg Alloy Interlayered with Cu Coating. Metals 2019, 9, 532 .

AMA Style

Amir Badamian, Chihiro Iwamoto, Shigeo Sato, Suguru Tashiro. Interface Characterization of Ultrasonic Spot-Welded Mg Alloy Interlayered with Cu Coating. Metals. 2019; 9 (5):532.

Chicago/Turabian Style

Amir Badamian; Chihiro Iwamoto; Shigeo Sato; Suguru Tashiro. 2019. "Interface Characterization of Ultrasonic Spot-Welded Mg Alloy Interlayered with Cu Coating." Metals 9, no. 5: 532.

Journal article
Published: 05 February 2019 in Applied Sciences
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In order to improvement electronic and mechanical properties, welding between stranded wires and terminals is important. However, welding methods to obtain high-quality joints using stranded wires are still limited. In this report, we applied ultrasonic welding to join a Cu stranded wire to a Cu substrate. Cross-sections of the weldments were taken and observed by several microscopy techniques to elucidate the weldability and soundness of the joints. After ultrasonic welding, each wire in the stranded wire was joined together at the region where the stranded wire was joined to the substrate without any defect. Each wire was welded through the Ag coating layer, and the stranded wire and the substrate was also welded through the outermost coating layers. It was found that ultrasonic welding is an efficient technique for producing high quality joints without any defect at the interface.

ACS Style

Chihiro Iwamoto; Keisuke Yamauchi; Kazuki Motomura; Yoichi Hashimoto; Kensuke Hamada. Microstructure of Joint between Stranded Wire and Substrate Welded by Ultrasonic Welding. Applied Sciences 2019, 9, 534 .

AMA Style

Chihiro Iwamoto, Keisuke Yamauchi, Kazuki Motomura, Yoichi Hashimoto, Kensuke Hamada. Microstructure of Joint between Stranded Wire and Substrate Welded by Ultrasonic Welding. Applied Sciences. 2019; 9 (3):534.

Chicago/Turabian Style

Chihiro Iwamoto; Keisuke Yamauchi; Kazuki Motomura; Yoichi Hashimoto; Kensuke Hamada. 2019. "Microstructure of Joint between Stranded Wire and Substrate Welded by Ultrasonic Welding." Applied Sciences 9, no. 3: 534.

Article
Published: 16 July 2018 in Metallurgical and Materials Transactions A
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Cu-Pd-Ag alloy wires with a relatively low Ag content are used widely in electronics. This alloy is usually subjected to age hardening to increase its strength. However, the alloy microstructure that results when the alloy is processed as a wire has not been clarified sufficiently to elucidate the hardening mechanism. A clarification of the microstructure is critical to control the mechanical properties of the alloy wire. In this study, we investigated the detailed microstructure variation of the alloy wire after heat treatment. Microscopy showed that the alloy wire contained many parallel rods with an Ag-rich α phase that extended along the axial direction of a Cu-rich α-phase matrix before heat treatment. After heat treatment at 623 K for 1 hour, the morphology of the rods in the matrix remained mostly unchanged. Detailed observations revealed that the matrix was transformed to a nanolamellar structure with β and α2 phases. Many β′ phases with a thickness of a few atomic layers precipitated in the rods. Both nanostructures investigated in this study were expected to contribute to wire hardening through a short-fiber strengthening mechanism.

ACS Style

Chihiro Iwamoto; Naoki Adachi; Fumio Watanabe; Risei Koitabashi. Microstructure Evolution in Cu-Pd-Ag Alloy Wires During Heat Treatment. Metallurgical and Materials Transactions A 2018, 49, 4947 -4955.

AMA Style

Chihiro Iwamoto, Naoki Adachi, Fumio Watanabe, Risei Koitabashi. Microstructure Evolution in Cu-Pd-Ag Alloy Wires During Heat Treatment. Metallurgical and Materials Transactions A. 2018; 49 (10):4947-4955.

Chicago/Turabian Style

Chihiro Iwamoto; Naoki Adachi; Fumio Watanabe; Risei Koitabashi. 2018. "Microstructure Evolution in Cu-Pd-Ag Alloy Wires During Heat Treatment." Metallurgical and Materials Transactions A 49, no. 10: 4947-4955.