Microstructure and Hardness of Bi-Containing Solder Alloys After Solidification and Ageing
Bibliographic record
Abstract
ABSTRACT This paper is focused on the microstructure and hardness analysis of new bismuth (Bi) containing alloys that have lower melting and process temperature than the conventional SAC305 solder alloy. One of the main SAC solder drawbacks is fast coarsening of microstructure resulting in degradation of the mechanical and thermomechanical properties during ageing. Seven Bi-containing alloys were used as listed in Table 1. Samples were aged for 25 and 100 hours at 100°C. Alloy hardness was measured after solidification ageing and quenching using a Rockwell hardness tester (HR15T scale with a 1/16” carbide ball indenter). The microstructures after solidification and after ageing were compared using scanning electron microscopy (SEM). The microstructures undergo significant changes upon ageing. Bi particles become uniformly distributed in the Sn matrix. While the hardness of SAC alloys is reduced after annealing, the hardness of these experimental alloys increases. The hardness gradually increases with increasing Bi content, as well as with increasing Ag content. The effect of solid solution strengthening and precipitation hardening mechanisms on microstructure and properties is discussed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".