Open AccessMicrostructure and Phase Investigation of Sn-58Bi-xCu Lead-Free Solder After Immersion in Sodium Chloride Solution
Author(s) -
Rabiatul Adawiyah Samsudin,
Wei Wong,
Muhammad Firdaus Mohd Nazeri,
Pramod K. Singh,
Rosli Othman,
Mohamad Najmi Masri
Publication year - 2021
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/2080/1/012026
Subject(s) - microstructure , intermetallic , materials science , metallurgy , ternary operation , corrosion , copper , chloride , tin , sodium , alloy , computer science , programming language
The changes in microstructure and phase of tin-bismuth-copper (Sn-58Bi-xCu) were investigated after immersion in 3.5 wt. % sodium chloride (NaCl) at variations of Cu micro-alloying at 0.25, 0.50, 0.75, 1.00 and 1.25 wt. %. The morphological observation revealed that the long crystal grains of the Cu-rich phase were produced as the amount of Cu increased. The phase analysis shows that at 0.5 wt. % Cu additions, the intermetallic compound od Cu 6 Sn 5 began to form and dominate the microstructure. After immersion in NaCl, a porous structure was seen covering the surface of the ternary solder, indicating the formation of a defective corrosion protection layer. The predominance of Cu 6 Sn 5 is believed to boost the galvanic corrosion coupling potential of the ternary solder. As a result, the more electrochemically reactive phase was pushed to be eliminated during immersion in 3.5 wt.% NaCl solution. Thus the black spots were formed. The presence of Cu 6 Sn 5 was seen to be detrimental to the electrochemical performance of Sn-58Bi-xCu.