Suppression of Cu3Sn in the Sn-10Cu peritectic alloy by the addition of Ni

Abstract

The effect of Ni additions on the peritectic reaction and phase formation in the Sn-10wt.%Cu alloy is investigated through cooling curve analysis, in situ synchrotron observation during alloy solidification, and microstructural analysis of as-cast alloy by optical and electron microscopy. More specifically, this study examined the effect of Ni to determine whether Cu 3 Sn can be completely suppressed. The results showed that the addition of Ni in the range of 0.06wt.%-1 wt.% completely suppressed the formation of primary Cu 3 Sn phase, and instead Cu 6 Sn 5 directly nucleates from the melt. It is proposed that increasing the amount of Ni decreases the amount of Cu 3 Sn until it is completely suppressed by shifting the Cu 3 Sn phase boundaries, such that Cu 6 Sn 5 forms throughout the microstructure. The results from this study provide an opportunity to better understand the solidification behaviour of Sn-10Cu alloys with Ni additions.

Rapid fabrication of tin-copper anodes for lithium-ion battery applications

“…This result is later confirmed by higher resolution observation under C s -corrected STEM. The lack of Cu 3 Sn at the Cu-6Ni/Sn interface is similar to the effects of Ni when it is present as an alloying addition in the Sn alloy instead of the Cu [21,22]. Cu 3 Sn does not react with Li as an active anode material at room temperature [23], decreasing the specific capacity of the electrode.…”

Morphologies of intermetallic compound phases in Sn-Cu and Sn-Co peritectic alloys during directional solidification

“…According to phase diagrams shown in Fig. 1, the Sn-32at.% Cu alloy experiences the solidification of the primary Cu 3 Sn phase at 530 ºC [23,26,27] : L→Cu 3 Sn, then the peritectic reaction at T P =415 ºC: L+Cu 3 Sn→Cu 6 Sn 5 , and the eutectic reaction at T E =231.96 ºC. The Sn-9at.% Co alloy experiences the solidification of the primary CoSn phase at 810 ºC: L→CoSn, the peritectic reaction at T P =525 ºC [31][32][33] : L+CoSn→CoSn 2 , and eutectic reaction at T E =231.96 ºC.…”

“…For the convenience of description, S i was defined as: Therefore, for a solid phase, the smaller S i means the smaller value of dΔS ST /dT, then the non-faceted morphology is more likely to occur. The values of m S and m L are usually obtained from the phase diagram [23,26,27] . Here, the Sn-Co peritectic alloy is taken as an example for analysis.…”

“…Among them, the Sn-Cu and Sn-Co alloys have shown wide application. As one of the most popular lead-free solders, Sn-Cu alloys are commonly applied in the electronics industry owing to their excellent weldability and non-toxic property [23][24][25][26][27][28][29] . Investigation on the Sn-Cu solders of high Sn content is of great interest since the operating temperature of solders can be enhanced by increasing the content of Cu.…”

“…Fig. 1: Sn-Cu (a) and Sn-Co (b) binary alloy phase diagrams where the red vertical lines show the composition of Sn-32at.% Cu and Sn-9at.% Co peritectic alloys in this work, respectively[23,31] …”