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

The effect of microstructure on the tensile–creep behavior of Mg–11Y–5Gd–2Zn–0.5Zr (wt.%) (WGZ1152) at 573 K (0.64Tm) 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 (∼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.

► The alloy exhibited excellent creep resistance at high temperature up to 573 K.
► Creep stress exponent (∼5) suggested dislocation creep was dominant mechanism.
► Minimum creep rate and fracture time followed the Monkman–Grant relationships.
► Microstructure evolution and its effect on creep behavior were investigated.
► In-situ creep experiment highlighted deformation/intergranular cracking evolution.