The creep behavior of a precipitation hardenable Mg-8Zn-4Al-0.5Ca (wt.%) casting alloy was determined by using impression creep tests in the temperature range of 403-623 K and under the punching stress range of 1.68-60.4 MPa. Using a power law between the steady-state impression velocity and the punching stress, it was found that the stress exponent changes with both stress and temperature. The activation energy evaluated at the same punching stress was found to be a function of the punching stress and changed from 76.5 kJ/mol at 13.4 MPa to 45.4 kJ/mol at 46.95 MPa. However, by using a hyperbolic sine stress law between the steady-state impression velocity and the punching stress, a single activation energy was found to be 77.5 kJ/mol, which is about half of the activation energy for lattice diffusion in Mg. A single mechanism of grain boundary fluid flow was proposed to be the controlling mechanism for the creep behavior of the Mg-8Zn-4Al-0.5Ca alloy under the testing conditions.
|Number of pages||6|
|Journal||Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing|
|State||Published - Nov 25 2005|
Bibliographical noteFunding Information:
This research is supported by NSF through a grant DMR-0211706 monitored by Drs. Guebre Tessema and Bruce A. MacDonald and Kentucky Science and Engineering Foundation through a grant KSEF-148-502-03-73.
- Activation energy
- Mg alloy
ASJC Scopus subject areas
- Materials Science (all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering