Tensile creep behavior and microstructure evolution of extruded Mg-10Gd-3Y-0.5Zr (wt%) alloy

The tensile creep behavior and microstructure evolution of the extruded Mg-10Gd-3Y-0.5Zr (wt%, GW103) alloy were investigated at temperatures from 523 K to 573 K and stresses from 30 MPa to 120 MPa. The peak-aged extruded GW103 alloy exhibited a minimum creep rate ranging from 3.49×10−8 s−1 to 2.43×10−6 s−1, and the aging treatment exerted limited effect on its creep performance. The measured stress exponent and activation energy of the peak-aged extruded alloy were 2.9±0.5 and 182.5±1.3 kJ/mol, respectively. Increasing precipitates formed during creep, which contributed to improving its creep-resistance. Precipitate free zones (PFZs) were observed in the tertiary stage near the boundaries which were perpendicular to the loading direction, and the formation of specially directional PFZs was demonstrated mainly stress-induced. Fractographic analysis revealed that intergranular ductile fracture was the main fracture mode after creep rupture. The low values of stress exponent and the formation of specially directional PFZs in the extruded alloy indicated that diffusion creep acted as a predominant mechanism.