Development and Characterization of Cast Modified SI-CU-MG Alloys for Heat Resistant Power Train Applications
Bibliographic record
Abstract
High temperature tensile, compression and low cycle fatigue tests were performed to assess the influence of micro-additions of Ti, V and Zr on the Al-7Si-1Cu-0.5Mg (wt.%) alloy in the as-cast and heat treated conditions. A combination of electron microscopy and high temperature X-ray diffraction was used to identify phases and temperature ranges of their thermal stability. The microstructure of the as-cast Al-7Si-1Cu-0.5Mg (wt.%) base and modified alloys consisted of α-Al, eutectic Si, and Cu-, Mg- and Fe-based phases Al2.1Cu, Al8.5Si2.4Cu, Al7.2Si8.3Cu2Mg6.9 and Al14Si7.1FeMg3.3. In addition, the micro-sized Ti/V/Zr-rich phases Al6.8Si1.4Ti, Al21.4Si4.1Ti3.5VZr3.9, Al6.7Si1.2TiZr1.8, Al2.8Si3.8V1.6Zr and Al5.1Si35.4Ti1.6Zr5.7Fe were identified in the modified alloys. During solution treatment, Cu- and Mg- based phases were completely dissolved, while the eutectic silicon, Fe- and Ti-V-Zr-rich intermetallics partially dissolved. The TEM analysis confirmed the presence of nano-sized precipitates of (AlSi)3(TiVZr) with D023 tetragonal crystal structure. The tensile tests of the alloy in the as-cast state showed that with increasing testing temperature from 25°C to 400°C the yield strength and tensile strength of the studied alloy decreased from 161 MPa to 84 MPa and from 261 MPa to 102 MPa, respectively. Accordingly, the T6 heat treated alloy modified with additions of a higher content of Ti-V-Zr achieved the highest tensile strength of 343 MPa over the base alloy and alloys modified with additions of Ti, Ti-Zr and lower contents of Ti-V-Zr. The fatigue life of the studied alloy in the T6 condition was substantially longer than those of the reference alloys A356 and the same Al-7Si-1Cu-0.5Mg base alloy with lower additions of V, Zr and Ti in the T6 condition. The fractography revealed tensile crack propagation through the eutectic Si and primary phases, exhibiting intergranular fracture along with some cleavage-like features of the plate-shaped Ti-V-Zr-rich intermetallics with a presence of fatigue striations on the latter, indicating their ductile nature. It is believed that the intermetallic precipitates containing Zr, Ti and V improve the fatigue life of the studied alloy in the T6 condition.
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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 | 0.001 |
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".