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

摘要

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.