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

Abstract

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 30MPa and 140MPa 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 (∼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