Development of weak-textured and high-performance Mg-Zn-Ca alloy sheets based on Zn content optimization

An intense texture is usually developed in conventional Mg alloys after deformation, resulting in unsatisfactory formability at room temperature. In the present work, a low-alloyed and weak-textured Mg-1.5Zn-0.2Ca (wt.%) alloy that exhibited an advantageous combination of strength and ductility was developed, with an ultimate strength of similar to 270 MPa and fracture elongation of similar to 30%. The role of Zn addition in the texture and microstructure evolution was systematically investigated. The Mg-xZn-0.2Ca (x = 0.5, 1.0, 1.5, and 2.0 wt%) alloys with increasing Zn content stored additional deformation energy, which accelerated the static recrystallization (SRX) process and resulted in a gradual weakening of the annealing texture. The co-addition of Zn and Ca contributed to the random SRX nucleation and the enhanced solute dragging effects by decreasing grain boundary energy, leading to a weaker texture in the Mg-1.5Zn-0.2Ca alloy than that in the Mg-1.5Zn and Mg-0.2Ca alloys after annealing. The excellent ductility of Mg-1.5Zn-0.2Ca alloy was attributed to the simultaneous increment of uniform elongation and post-uniform elongation as Zn content increases, benefited from its weakened texture and improved failure mode, respectively. This work provides valuable insights into the development of novel low-alloyed Mg sheets with a weak texture, which possess great potential for direct forming to near-net-shaped products without tearing and fracturing. (C) 2020 Elsevier B.V. All rights reserved.