Effects of Yttrium Addition on the Microstructure Evolution and Electrochemical Corrosion of SN-9Zn Lead-Free Solders Alloy

• Published in: Materials Vol. 14; no. 10; p. 2549
• Main Authors: Yang, Wenchao, Mao, Jun, Ma, Yueyuan, Yu, Shuyuan, He, Hongping, Qi, Da, Zhan, Yongzhong
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 14-05-2021; MDPI
• Subjects: Aeration; Alloys; Corrosion effects; Corrosion resistance; Corrosion resistant alloys; Electrochemical corrosion; Electrode polarization; Electrodes; Evolution; Grain refinement; Grain size; Lead free; lead-free solder; Mechanical properties; Melting points; Microstructure; microstructure evolution; Morphology; Sn-Zn; Sodium chloride; Solders; Substrates; Tin; Tin base alloys; Wettability; Yttrium; Zinc; China; Japan
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14102549

Electrochemical corrosion behavior of ternary tin-zinc-yttrium (Sn-9Zn-xY) solder alloys were investigated in aerated 3.5 wt.% NaCl solution using potentiodynamic polarization techniques, and the microstructure evolution was obtained by scanning electron microscope (SEM). Eight different compositions of Sn-9Zn-xY (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, and 0.30 wt.%) were compared by melting. The experimental results show that when the content of Y reached 0.06 wt.%, the grain size of Zn-rich phase became the smallest and the effect of grain refinement was the best, but there was no significant effect on the melting point. With the increases of Y content, the spreading ratio first increased and then decreased. When the content of Y was 0.06 wt.%, the Sn-9Zn-0.06Y solder alloy had the best wettability on the Cu substrate, which was increased by approximately 20% compared with Sn-9Zn. Besides, the electrochemical corrosion experimental shows that the Y can improve the corrosion resistance of Sn-9Zn system in 3.5 wt.% NaCl solution, and the corrosion resistance of the alloy is better when the amount of Y added is larger within 0.02–0.30 wt.%. Overall considering all performances, the optimal performance can be obtained when the addition amount of Y is 0.06.