Creep behavior of hot extruded Al-Al2O3 nanocomposite powder

A commercial gas-atomised aluminium powder was mechanically milled in a planetary ball mill under an argon atmosphere for 12 h to produce alumina dispersion-strengthened aluminium powder. TEM revealed that about 2 vol% alumina particles with an average size of 100 nm were distributed in the aluminiu...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2010-04, Vol.527 (10-11), p.2567-2571
Main Authors: HOSSEINI MONAZZAH, A, SIMCHI, A, SEYED REIHANI, S. M
Format: Article
Language:English
Subjects:
Aluminium
Aluminum
Aluminum oxide
Applied sciences
Billets
Creep
Creep (materials)
Dislocations
Dispersion hardening metals
Exact sciences and technology
Extrusion
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metals. Metallurgy
Nanostructure
Powder metallurgy. Composite materials
Production techniques
Technology
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Summary:A commercial gas-atomised aluminium powder was mechanically milled in a planetary ball mill under an argon atmosphere for 12 h to produce alumina dispersion-strengthened aluminium powder. TEM revealed that about 2 vol% alumina particles with an average size of 100 nm were distributed in the aluminium matrix. The nanocomposite powder was canned in an aluminium container, vacuum de-gassed, and hot extruded at 723 K at an extrusion ratio of 16:1. The creep behaviour 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, indicating that detachment of dislocations from the Al2O3 nanoparticles occurred during the high-temperature deformation. The threshold stress was 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 behaviour is explained according to the invariant substructure model and dislocation glide process.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2010.01.060