Influence of cobalt content on microstructure and corrosion performance of extruded Sn-9Zn solder alloys

• Published in: Journal of Central South University Vol. 27; no. 3; pp. 711 - 720
• Main Authors: Jiang, Shou-li, Zhong, Jian-feng, Li, Jia-yuan, Wang, Ri-chu, Peng, Chao-qun, Cai, Zhi-yong
• Format: Journal Article
• Language: English
• Published: Changsha Central South University 01.03.2020; Springer Nature B.V
• Subjects: Cobalt; Corrosion; Corrosion prevention; Engineering; Eutectic reactions; Eutectic temperature; Extrusion; Intermetallic compounds; Lead free; Melting points; Metallic Materials; Microstructure; Morphology; Precipitates; Solders; Tin base alloys; 钴含量; Sn-9Zn solder alloy; 显微组织; microstructure; Sn-9Zn 焊料; extrusion; cobalt addition; 挤压; 腐蚀性能; corrosion performance
• ISSN: 2095-2899; 2227-5223
• DOI: 10.1007/s11771-020-4325-y

The Pb-free solders have attracted a great deal of attention recently due to the environmental concerns. The present work focuses on the effect of cobalt content (0, 0.5 and 3.0) on the microstructural characteristics, melting point and corrosion performance of extruded Sn-9Zn solder alloys. The results reveal that the Zn-rich precipitates with spherical or needle-like shape in the Sn-9Zn- x Co alloys are refined remarkably by forming the γ -Co 5 Zn 21 and Co 2 Sn 2 Zn Co-contained intermetallic compounds, though the melting point and eutectic reaction temperature decrease slightly. It is suggested that the corrosion property of the extruded Sn-9Zn- x Co alloys is improved significantly by adding the cobalt element, while the content should be controlled reasonably. Combining the corrosion morphology, the influence of cobalt content on the corrosion behavior of the Sn-9Zn- x Co alloys is analyzed in terms of the refined microstructure and the enhanced passive film stability.