Precipitation Evolution in Al-0.1Sc, Al-0.1Zr and Al-0.1Sc-0.1Zr (at.%) Alloys During Isochronal Aging

Abstract

Precipitation strengthening is investigated in binary Al-0.1Sc, Al-0.1Zr and ternary Al-0.1-c-0.1Zr (at.%) alloys aged isochronally between 200 and 600 C. Precipitation of Al3Sc (L12) commences between 200 and 250 C in Al-0.1Sc, reaching a 670 MPa peak microhardness at 325 C. For Al-0.1Zr, precipitation of Al3Zr (L12) initiates between 350 and 375 C, resulting in a 420 MPa peak microhardness at 425-450 C. A pronounced synergistic effect is observed when both Sc and Zr are present. Above 325 C, Zr additions provide a secondary strength increase from the precipitation of Zr-enriched outer shells onto the Al3Sc precipitates, leading to a peak microhardness of 780 MPa at 400 C for Al-0.1Sc-0.1Zr. Compositions, radii, volume fractions and number densities of the Al3(Sc1 xZrx) precipitates are measured directly using atom-probe tomography. This information is used to quantify the observed strengthening increments, attributed to dislocation shearing of the Al3(Sc1 xZrx) precipitates.

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Document Details

Document Type
Technical Report
Publication Date
May 27, 2010
Accession Number
ADA526329

Entities

People

  • Constance P. Lee
  • David C. Dunand
  • David N. Seidman
  • Keith E Knipling
  • Richard A. Karnesky

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Binary Alloys
  • Boundaries
  • Chemical Analysis
  • Detection
  • Dislocations
  • Dispersion Hardening
  • Electrical Conductivity
  • Electron Microscopy
  • Hardness
  • Materials
  • Materials Science
  • Measurement
  • Mechanical Properties
  • Microhardness
  • Shear Strength
  • Solid Solutions
  • Tomography

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  • Materials Science and Engineering.
  • Reinforced Composite Materials