Reactions In The Sn Corner of the Cu-Sn-Zn Alloy System
Bibliographic record
Abstract
ABSTRACT In view of potential damage to heat sensitive electronic components during soldering at the high temperatures required for some Pb-free solders, such as the SAC alloys, it appears likely that more use will be made of solders based on the much lower melting Sn-Zn eutectic alloy. Consequently, it is of interest to determine what reactions can occur in ternary systems derived from the Sn-Zn eutectic. One such system is Cu-Sn-Zn. This paper reports a number of experimentally determined reactions that occur in Sn-rich alloys of this ternary system. In the expectation of a possible connection between the Sn- Cu6Sn5 and Sn-Zn binary eutectics, several alloy compositions were selected along a possible joining path. Samples of each were solidified unidirectionally at a very slow rate, approximating freezing with complete mixing in the liquid (the “Solidification Path” technique). This procedure allows detection of reactions by the change in the phases frozen out with change in composition of the liquid due to segregation. Three quasiperitectic reactions (U1-U3) and a ternary eutectic reaction were found: U1: L+Cu6Sn5↔CuZn+Sn U2: L+CuZn↔Cu5Zn8+Sn U3: L+Cu5Zn8↔CuZn4+Sn E: L↔(Sn)+(Zn)+CuZn4 It is shown theoretically and confirmed experimentally that each of these three quasiperitectic reactions can produce, on a copper substrate, the undesirable effect known as “spalling” in which multiple layers of different phases are formed at the solder-substrate interface during freezing.
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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 | 0.000 | 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".