Interface structure characterization of Fe36Ni alloy with ultrasonic soldering

• Published in: Journal of alloys and compounds Vol. 576; pp. 386 - 392
• Main Authors: Wei, Jinghui, Deng, Binghui, Gao, Xingqiang, Yan, Jiuchun, Chen, Xiaoguang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 05.11.2013; Elsevier
• Subjects: Applied sciences; Brazing. Soldering; Compressive strength; Condensed matter: structure, mechanical and thermal properties; Diffusion; Diffusion in solids; Exact sciences and technology; Fatigue, brittleness, fracture, and cracks; Ferrous alloys; Fracture mechanics; Interface structure and roughness; Intermetallic compounds; Intermetallics; Joining, thermal cutting: metallurgical aspects; Liquid–solid reactions; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals and alloys; Metals. Metallurgy; Microstructure; Phase transformations; Physics; Scanning electron microscopy; SEM; Silicon; Solders; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Transport properties of condensed matter (nonelectronic); Ultrasonic soldering; Scanning electron microscopy; Metals and alloys; Microstructure; Diffusion; Liquid–solid reactions; Ruptures; Intermetallic compounds; Fillers; Ultrasonic waves; Shear strength; Liquid―solid reactions; Scanning electron microscopy, SEM; Compression strength; Thickness; Interfaces; Interface structure; Solder; Cracks; Fractures; Eutectics; Stress effects; Liquid solid reaction; Soldered joints; Soldering; Double layers
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.05.085

•Fe36Ni joint microstructures using ZnAl(Si) by ultrasonic soldering are compared.•Γ-Fe4Zn9 and Γ2-Fe6Ni5Zn89 phases are identified on the ZnAl/Fe36Ni interface.•A reaction layer approximately 0.1μm thick appears on the ZnAlSi/Fe36Ni interface.•Shear strength of the joints using ZnAlSi solder reaches as high as 102–115 MPa.•A reaction model is presented to analyze the function mechanism of Si. The ultrasonic soldering of Fe36Ni alloy using Zn-based filler metal (with and without Si) has been investigated at 420°C. For the solder without Si, apparent double reaction layers formed at the Fe36Ni and ZnAl interfaces, including the Γ-Fe4Zn9 facing Fe36Ni alloy and Γ2-Fe6Ni5Zn89 upon which numerous cracks had grown into the solder. When 0.4wt% Si was added to the solder, the bond microstructure was the Zn–Al eutectic phase and η-Zn phase without cracks; only a thin intermetallic compound with constant thickness was formed on the ZnAlSi/Fe36Ni interface even though the process parameters had changed. Joints using ZnAlSi solder reached the highest compressive shear strength of approximately 102–115MPa with their fracture paths propagating primarily through the intermetallic compound layers at the ZnAlSi/Fe36Ni interface. The mechanism for the effect of Si is explored through a reaction model of the ZnAl(Si)/Fe36Ni system with ultrasonic soldering. This study provides a joining method characterized by low temperature and low stress for low-expansion alloys.