Temporal evolution of the nanostructure of Al(Sc,Zr) alloys: Part II-coarsening of Al3(Sc1-xZrx) precipitates

The coarsening behavior of four Al(Sc,Zr) alloys containing small volume fractions ( < 0.01) of Al3(Sc, _,Zr,) (L12) precipitates was investigated employing conventional transmission electron microscopy (CTEM) and high-resolution electron microscopy (HREM). The activation energies for diffusion-l...

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Bibliographic Details
Published in:Acta materialia 2005-12, Vol.53 (20), p.5415-5428
Main Authors: FULLER, Christian B, SEIDMAN, David N
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Metals. Metallurgy
Online Access:Get full text
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Summary:The coarsening behavior of four Al(Sc,Zr) alloys containing small volume fractions ( < 0.01) of Al3(Sc, _,Zr,) (L12) precipitates was investigated employing conventional transmission electron microscopy (CTEM) and high-resolution electron microscopy (HREM). The activation energies for diffusion-limited coarsening were obtained employing the Umantsev-Olson-Kuehmann-Voorhees (UOKV) model for multi-component alloys. The addition of Zr is shown to retard significantly the coarsening rate and stabilize precipitate morphologies. HREM of Al(Sc,Zr) alloys aged at 300 DGC reveals Al3(Sc1-XZr,) precipitates with sharp facets parallel to {100} and {110} planes. Coarsening of Al-0.07 Sc-0.019 Zr at.%, A1-0.06 Sc-0.005 Zr at.% and Al-0.09 Sc-0.047 Zr at.% alloys is shown to be controlled by volume diffusion of Zr atoms, while coarsening of Al-0.14 Sc-0.012 Zr at.% is controlled by volume diffusion of Sc atoms.
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2005.08.015