Mechanical properties and optimization of the aging of a dilute Al-Sc-Er-Zr-Si alloy with a high Zr/Sc ratio

Anthony De Luca*, David C. Dunand, David N. Seidman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

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 languageEnglish (US)
Pages (from-to)35-42
Number of pages8
JournalActa Materialia
Volume119
DOIs
StatePublished - 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

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