Effect of Er additions on ambient and high-temperature strength of precipitation-strengthened Al-Zr-Sc-Si alloys

Christopher Booth-Morrison, David N. Seidman, David C. Dunand*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

106 Scopus citations

Abstract

The effect of substituting 0.01 at.% Er for Sc in an Al-0.06Zr-0.06Sc-0. 04Si (at.%) alloy subjected to a two-stage aging treatment (4 h/300°C and 8 h/425°C) is assessed to determine the viability of dilute Al-Si-Zr-Sc-Er alloys for creep applications. Upon aging, coherent, 2-3 nm radius, L1 2-ordered, trialuminide precipitates are created, consisting of an Er- and Sc-enriched core and a Zr-enriched shell; Si partitions to the precipitates without preference for the core or the shell. The Er substitution significantly improves the resistance of the alloy to dislocation creep at 400°C, increasing the threshold stress from 7 to 10 MPa. Upon further aging under an applied stress for 1045 h at 400°C, the precipitates grow modestly to a radius of 5-10 nm, and the threshold stress increases further to 14 MPa. These chemical and size effects on the threshold stress are in qualitative agreement with the predictions of a recent model, which considers the attractive interaction force between mismatching, coherent precipitates and dislocations that climb over them. Micron-size, intra- and intergranular, blocky Al 3Er precipitates are also present, indicating that the solid solubility of Er in Al is exceeded, leading to a finer-grained microstructure, which results in diffusional creep at low stresses.

Original languageEnglish (US)
Pages (from-to)3643-3654
Number of pages12
JournalActa Materialia
Volume60
Issue number8
DOIs
StatePublished - May 2012

Keywords

  • Aluminum alloys
  • Erbium
  • Precipitation
  • Scandium
  • Zirconium

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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