Creep behavior of Mg-11Y-5Gd-2Zn-0.5Zr (wt.%) at 573

The effect of microstructure on the tensile-creep behavior of Mg-11Y-5Gd-2Zn-0.5Zr (wt.%) (WGZ1152) at 573K (0.64T(m)) and stresses between 30 MPa and 140 MPa was investigated. The minimum creep rate of the peak-aged (T6) alloy was almost two orders of magnitude lower than that for a WE54-T6 (Mg-5.2Y-3.6RE-0.5Zr (wt.%)) alloy. The peak-aged condition (T6) exhibited slightly greater creep resistance than the as-cast condition. The solution treated (T4) material exhibited the lowest creep resistance. The creep stress exponent (similar to 5) suggested that dislocation creep was the dominant secondary creep mechanism. The minimum creep rate and time-to-fracture could be described by the Monkman-Grant equation. An in-situ creep experiment indicated that intergranular cracking was prevalent in the tertiary creep regime and the crack propagation path tended to follow the grain boundaries. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.