Results
3.1. Microstructure
Fig. 2 shows the microstructure of as-cast and as-rolled
Mg-5Li-1Al-0.5Y alloys. The grain size of the as-cast alloy is
the largest among the four specimens, and some black secondary
phases exist in the alloy. Zhu et al. [12] reported that the
black secondary phase is Al2Y. Compared with Fig. 2a, the
grain size of the as-rolled specimens is much smaller (shown in
Fig. 2b, c and d); sheet 3 possesses the smallest and comparatively
more uniform grain size. The Al2Y compounds still exist
in the specimens, but most of them are crushed into fine particles.
Few bulk Al2Y phase could also be found in sheet 1 and
sheet 2. While in sheet 3, only some tiny particulate phase
distributes in the grains. Fig. 3 is the microstructure of sheet 1
before annealing. Many twins apparently distribute in grains.
Compared with Fig. 2, after annealing treatment, there exists
almost no twins in the grains.