Bidirectional pulsed current effect on the precipitation behavior of Cu6Sn5: An in situ observation

Abstract Cu6Sn5 plays an important role in tin-based babbitt alloys and microelectronic interconnections. This study used the in situ synchrotron X-ray radiography to study the effect of bidirectional pulse currents on the precipitation behavior of Cu6Sn5. The Boltzmann cumulative distribution function was used as a model for fitting the grain density versus temperature, where R2 ≥ 0.995 confirms a good correlation of the model with experimental data. The results show that bidirectional pulsed currents can effectively control the initial nucleation temperature, maximum nucleation rate, and final grain density. In addition, bidirectional pulsed current affects the growth morphology of Cu6Sn5. The thorn-like growth morphology is facilitated with the current density increasing from 0 A/cm2 to 50 A/cm2, but it is suppressed with the current density increasing from 50 A/cm2 to 200 A/cm2. This study improves the fundamental understanding of nucleation and growth behavior of Cu6Sn5 under bidirectional pulsed current and provides guidance for controlling the size and morphology of Cu6Sn5.