Lightweight, High-Strength, Age-Hardenable Nanoscale Materials
Final rept. 15 Dec 2000-30 Jun 2003
CINCINNATI UNIV OH DEPT OF CHEMICAL AND MATERIALS ENGINEERING
Pagination or Media Count:
Phase transformations and precipitation behavior in age-hardenable nanoscale materials, using binary aluminum alloys as model materials, were studied. Nanoparticles of Al-Cu and Al-Zn were synthesized by a plasma ablation process. The particles 50-100 nm dia were found to be supersaturated f.c.c. and were enveloped by a 2-4 nm amorphous Al oxide layer. On aging the Al-Cu nanoparticles, a precipitation sequence comprising nearly pure Cu precipitates to theta to the equilibrium theta was observed, with all three forming along the Al oxide-matrix interface. In the Al-Zn nanoparticles, a spinodal structure was noted in the as-synthesized state, which evolved into a striated, f.c.c. twinned platelet structure within which were contained hcp precipitates also in twin relation nearly pure Zn- precipitates also formed along the Al oxide-matrix interface. Ultra fine Al-Cu nanoparticles were also synthesized by inert gas condensation these were found to be quite stable against precipitation during aging. Finally, the results revealed that Al nanopowders could be processed into bulk structures, leading to interesting Al-Al oxide nanocomposites with full densification and high hardness.
- Physical Chemistry
- Properties of Metals and Alloys