TY - JOUR
AU - Unigovski, Yakov B.
PY - 2017/04/15
Y2 - 2023/12/09
TI - Creep-rupture behavior of die-cast magnesium alloys
JF - Journal of Metals, Materials and Minerals
JA - J Met Mater Miner
VL - 19
IS - 1
SE - Original Research Articles
DO -
UR - https://jmmm.material.chula.ac.th/index.php/jmmm/article/view/216
SP -
AB - It is found that the relationship between the time-to-rupture <em>t</em><sub>r</sub> and the time to the onset of tertiary creep <em>t</em><sub>Î¿t</sub> (<em>t</em><sub>r</sub>/<em>t</em><sub>ot</sub>) in die-cast Mg-9Al alloy is equal to 1.3 and independent of stress, test temperature and diecasting parameters over the range examined. It is shown that the introduction of creep-rupture strain into Monkman-Grant relation modified by DobeÅ¡ and MiliÄka demonstrates only the deviation range of the minimum creep rate from the average creep rate. The apparent activation energy E<sub>c</sub> of creep is below the value of magnesium self-diffusion energy ESD up to 175Â°C. At higher temperatures, E<sub>c</sub> > E<sub>SD</sub>, and creep deformation may be controlled by diffusion processes (dislocation climbing, etc.). The established magnitude of stress exponent n in the power law (the modified Arrhenius rate equation) within the stress range from 20 to 50 MPa is close to the value of n â‰… 3 typical of solid-solution alloys. The increase in n values at higher stresses up to ~ 5 is caused, probably, by stress-induced precipitation of Î²-phase during long-term creep tests.
ER -