About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
|
| Symposium
|
Electronic Packaging and Interconnection Materials IV
|
| Presentation Title |
Evolution of Microstructure and Micro-hardness in Room-Temperature Aged Sn-5wt%Bi Alloys: A Quasi In-Situ Study on Precipitation Kinetics |
| Author(s) |
Yung-Chuan Chiang, Chien-Lung Liang |
| On-Site Speaker (Planned) |
Yung-Chuan Chiang |
| Abstract Scope |
According to the Sn-Bi binary phase diagram, Sn-5 wt% Bi alloys exhibit only 2 wt% Bi particles at room temperature (25°C). In this study, unexpected surface precipitation of Bi in the solution-treated Sn-5 wt% Bi alloy was observed. Specifically, the area fraction of Bi precipitates increased from 4.3 ± 1.7% (0 h) to 10.2 ± 4.5% (24 h), and reached 16.0 ± 4.7% (equivalent to ~20 wt% Bi) after 120 h of natural aging. Concurrently, Vickers micro-hardness decreased from 29.0 ± 0.2 HV to 26.3 ± 0.5 HV within 24 h, followed by a gradual rebound to 28.2 ± 0.1 HV over the subsequent 360 h. The evolution of surface precipitation and micro-hardness suggests a competition between solid solution strengthening and precipitation hardening of Sn-5 wt% Bi alloys. The quasi in-situ SEM (scanning electron microscope) investigation further demonstrated a specific precipitation pathway, with phase transformation kinetics revealed. |
| Proceedings Inclusion? |
Planned: TMS Journal: Journal of Electronic Materials |
| Keywords |
Characterization, Phase Transformations, Mechanical Properties |