Creep of Al-Sc Microalloys with Rare-Earth Element Additions

Abstract:

Cast and aged Al-Sc microalloys are creep-resistant to 300‰, due to the blocking of dislocations by nanosize, coherent Al3Sc (L12) precipitates. Rare-earth elements substitute for Sc in these precipitates, leading to a higher number density of smaller precipitates, which have a greater lattice-parameter mismatch with Al than in the Al-Sc binary microalloy. This leads to an improvement in both ambient temperature microhardness and high temperature creep. Creep threshold stresses of Al-Sc-RE (RE = Y, Dy, or Er) at 300‰ are higher than for Al-Sc and Al-Sc-M (M = Mg, Ti, or Zr) microalloys. This is in agreement with a dislocation climb model that includes the elastic stress fields of the precipitates.

• Periodical: Materials Science Forum (Volumes 519-521)
• Pages: 1035-1040
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.519-521.1035
• Online since: July 2006
• Authors: Richard A. Karnesky, David N. Seidman, David Dunand
• Keywords: Creep, Precipitation Strengthening, Rare Earth Element (REE), Sc

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