Loading...

Creep behavior of hot extruded Al-Al2O3 nanocomposite powder

Hosseini Monazzah, A ; Sharif University of Technology | 2010

1725 Viewed
  1. Type of Document: Article
  2. DOI: 10.1016/j.msea.2010.01.060
  3. Publisher: 2010
  4. Abstract:
  5. A commercial gas-atomized aluminum powder was mechanically milled in a planetary ball mill under an argon atmosphere for 12 h to produce alumina dispersion strengthened aluminum powder. Transmission electron microscopy (TEM) revealed that about 2 vol.% alumina particles with an average size of 100 nm were distributed in the aluminum matrix. The nanocomposite powder was canned in an aluminum container, vacuum de-gassed, and hot extruded at 723 K at an extrusion ratio of 16:1. The creep behavior of the extruded billet in the direction of extrusion was examined at a constant applied load ranging from 10 to 40 MPa at temperatures of 648, 673 and 723 K. A threshold creep-stress was noticed which indicates that detachment of dislocations from the Al2O3 nanoparticles occurred during the high-temperature deformation process. The threshold stress was found to be temperature dependent as it decreased from 8.3 MPa at 648 K to 2.7 MPa at 723 K. The stress exponent index also decreased from 8 to 3, revealing a change in the creep mechanism by increasing the testing temperature. The creep behavior is explained according to the invariant substructure model and dislocation glide process
  6. Keywords:
  7. Al-Al2O3 ; Nanocomposite ; Al-Al2O3 ; Alumina dispersions ; Alumina particles ; Aluminum matrix ; Aluminum powders ; Applied loads ; Argon atmospheres ; Average size ; Creep behaviors ; Creep mechanism ; Dislocation glide ; Extruded billets ; Extrusion ratio ; High temperature deformation ; Nanocomposite powder ; Planetary ball mill ; Stress exponents ; TEM ; Temperature dependent ; Testing temperature ; Threshold stress ; Aluminum containers ; Aluminum powder metallurgy ; Argon ; Ball milling ; Ball mills ; Creep ; Creep testing ; Extrusion ; Mechanical alloying ; Metallurgy ; Nanocomposites ; Stresses ; Transmission electron microscopy ; Aluminum
  8. Source: Materials Science and Engineering A ; Volume 527, Issue 10-11 , 2010 , Pages 2567-2571 ; 09215093 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0921509310000924