The aging behaviour of a Mg-10Gd-3Y-1.0Zn-0.5Zr (wt.%) alloy with long-period stacking ordered phase at 275°C

We investigated the aging behaviour of a Mg-10Gd-3Y-1.0Zn0.5Zr (wt.%) alloy with long-period stacking ordered (LPSO) phase at 275 degrees C. Its peak hardness is about 116.4 HV after aging for 25 h. We unravelled the evolution of prismatic precipitates through transmission electron microscopy (TEM). The formation process is 0 ' (10h)- 0 ' + 01 (15 h)- 0 ' + 01 + 0 (>= 20 h), where nano-scale b ' F phase benefits the transformation from 0 ' phase to 01 phase. In addition to the stable basal LPSO structures, the coexistence and competition balance between the prismatic 0 ', 01 and 0 phases synergistically contribute to the high hardness of the aged alloy. The number density of the prismatic precipitates is at the magnitude of 1020/m3. These prismatic precipitates during aging largely determine the hardness of the Mg alloys. The interaction between precipitates and stacking faults brings good compression property.