Abstract
Precipitation strengthening behavior during aging of an Al-0.014Sc-0.008Er-0.08Zr-0.10Si (at.%) alloy was investigated utilizing microhardness, electrical conductivity and scanning electron microscopy. This new composition, with a Sc/Zr ratio (in at.%) smaller than 1/5 represents a significant reduction of the alloy's cost, when compared to more usual Al-0.06Sc (at.%) based alloys with typical Sc/Zr ratios of 3. The research presented herein focuses on identifying the optimal homogenization duration at 640 °C and additionally the temperature range at which a single-step aging treatment will achieve the highest possible microhardness in the shortest time. Due to a compromise between dissolution of Er-Si rich primary precipitates, homogenization of the Zr distribution and precipitation of large Al3Zr precipitates, 8 h at 640 °C appears to be the optimal homogenization duration for this alloy, leading to an hardness of 571 ± 22 MPa after aging for 24 h at 400 °C. To study the precipitation behavior of this low-Sc concentration alloy, isochronal aging to 575 °C with two different heating rates was performed. The small Sc concentration, compensated by a high Zr concentration, permits the alloy to achieve a similar peak microhardness during isochronal aging (587 ± 20 MPa) as the corresponding Sc-richer and Zr-leaner alloys. The isochronal aging experiments permits us to identify the best aging temperature as between 350 and 425 °C.
Original language | English (US) |
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Pages (from-to) | 35-42 |
Number of pages | 8 |
Journal | Acta Materialia |
Volume | 119 |
DOIs | |
State | Published - Oct 15 2016 |
Keywords
- Al-Sc-Er-Zr-Si alloy
- High-temperature alloy
- Mechanical properties
- Microhardness
- Precipitation strengthening
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys