About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
|
| Symposium
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Phase Stability, Phase Transformations, and Reactive Phase Formation in Electronic Materials XXVI
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| Presentation Title |
The Influence of Undercooling on β-Sn Nucleation and Crystallographic Selection in Near-Eutectic Sn–58Bi Solder |
| Author(s) |
Xiaomei Shen, Christopher Gourlay |
| On-Site Speaker (Planned) |
Xiaomei Shen |
| Abstract Scope |
The role of primary (Bi) particles in reducing undercooling and promoting β-Sn nucleation in near-eutectic Sn–58Bi solder was investigated using differential scanning calorimetry (DSC), controlled isothermal treatments, scanning electron microscopy, and electron backscatter diffraction (EBSD). Primary (Bi) particles were generated by holding solder balls within the L+(Bi) phase field prior to cooling. Their presence reduced β-Sn nucleation undercooling from 11–22 K to 9–12 K and frequently changed solidification from a single β-Sn nucleation event to multiple β-Sn dendrites. β-Sn halos surrounding primary (Bi) particles suggest that local compositional changes during (Bi) growth promote β-Sn nucleation. EBSD analysis revealed strong crystallographic selection, with OR-1 observed in 17 of 28 primary (Bi)/β-Sn pairs and OR-2 in 5 of 28 pairs. The results demonstrate that primary (Bi) particles influence both the undercooling and crystallographic selection of β-Sn nucleation, providing new insight into microstructure development in low-temperature solder alloys. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Electronic Materials, Characterization, Solidification |