Microstructure, texture and mechanical properties of the rolled high modulus Mg-Y-Zn-Al-Li alloy

TLDR: In this paper, a new as-cast Mg-Y-Zn-Al-Li alloy with a high elastic modulus of 52.9 GPa was designed, which was further subjected to hot deformation under different rolling reductions (40% and 80%).

Abstract: In our previous work, we designed a new as-cast Mg–Y–Zn–Al–Li alloy with a high elastic modulus of 52.9 GPa. The alloy was further subjected to hot deformation under different rolling reductions (40% and 80%) in this work. The microstructure evolution, texture and mechanical properties of Mg–Y–Zn–Al–Li alloy compared with Mg–Y–Zn alloy were systematically investigated. The result showed that the Mg–Y–Zn–Al–Li alloy with a rolling reduction of 40% displayed a more homogeneous fine microstructure and a weakened basal texture, accompanied by the formation of Al–Li and nano-precipitates Al0.9Li34.3Mg64.5Zn0.3 phase. Compared with the Mg–Y–Zn alloy, the strength and ductility of the alloy also were obviously enhanced while possessing a weak mechanical anisotropy. Grain refinement and second phase strengthening (fine Al–Li phase and nano-precipitates Al0.9Li34.3Mg64.5Zn0.3) mainly contributed to the enhanced strength. The texture weakening, low dislocation density and non-basal slip commonly guaranteed the high ductility, especially the weakened texture gave rise to the low anisotropy. When the rolling reduction increased to 80%, the volume fraction of recrystallized grains in Mg–Y–Zn–Al–Li alloy increased significantly to73.3%. As a result, the symmetry of the texture distribution around the ND was appreciably improved. In addition, the lower dislocation density and more non-basal slip in the Mg–Y–Zn–Al–Li alloy with the rolling reduction of 80% further enhanced the ductility. Simultaneously, the anisotropic degree of mechanical was effectively minimized, which was mainly attributed to the weak symmetric texture caused by fine DRXed grains with random misorientation and non-basal pyramidal slip.