Twin-assisted precipitation during hot compression of an Mg-Gd-Zn-Zr magnesium alloy

Abstract

Dynamic precipitation in an Mg-Gd-Zn-Zr alloy during hot compression at 350℃ and 450℃ and at strain rates of 0.001-0.1s-1 is investigated. The deformation conditions were designed such as to promote twinning or slip of dislocations. The results indicated that both twinned and non-twinned grains were present at 350℃, with the extent being a function of the applied strain rate. The formation and propagation of {101 ̅ 2}〈1 ̅ 011〉 primary tensile twins within the twinned grains was identified as being at root of the twin-assisted precipitation phenomenon. The precipitates had spherical-morphology in the twinned grains whereas parallel arrays of rod-shaped precipitates formed in the non-twinned grains due to dynamic precipitation on the slip bands and the stacking faults. Twin-assisted precipitates were suppressed by increases in the strain rate at 350℃ because of the shorter time required for solute element diffusion towards the nucleated precipitates at that temperature. Increasing the deformation temperature to 450℃ changed the dominant deformation

Analysis of defects in a twin roll cast Mg‐Y‐Zn magnesium alloy

“…This phase has been mentioned in previous studies, mainly for Mg-Gd-Zn alloys. [32][33][34][35] Based on the contents of Zn and RE, slight variations in chemical composition as well as lattice parameters may occur.…”

“…However, in some Mg-Gd-Zn alloys the (Mg,Zn) 3 Gd or for rare earth containing magnesium alloys the (Mg,Zn) 3 RE phase is reported. [32][33][34] Saadati et al 32 found that the (Mg,Zn) 3 Gd phase precipitates dynamically under compressive load. It was therefore assumed that, as a result of the special solidification conditions in the center of the strip and the combined rolling during TRC of the WZ73 alloy, the (Mg,Zn) 3 Y phase was formed.…”