Enhanced strength and ductility of wrought magnesium alloys through alloying with rare earth elements

当今发达世界面临的挑战促使人们对用于交通运输的轻合金（如镁合金）产生了强烈的需求。尽管变形镁合金具有许多吸引人的性能，但由于低温成形性不足，其应用仍然受到限制，这直接归因于在热机械加工过程中组织和组织发育不充分。与典型的变形镁合金（如AZ31， ZK60）相比，含有稀土（RE）的镁合金会产生与强机械各向异性相关的尖锐变形织构，而含有稀土（RE）的镁合金则会产生更弱和更不常见的织构，有助于增强环境成形性和降低机械各向异性。虽然已经报道了添加稀土对纹理随机化的影响，但所观察到的纹理改变的机制仍未得到最终的理解。该项目的目的是对镁稀土合金的变形和再结晶进行全面的研究，为优化强度和延展性的镁变形合金的设计策略提供新的思路。主要研究了稀土元素添加量对合金变形特性、再结晶机制和织构发育的影响。通过确定控制机制，我们应该能够推导出优化力学性能的微观结构和织构工程概念。

The challenges of today's advanced world are enforcing a strong demand for light alloys based for e.g. on magnesium to be used in transportation. Despite many attractive properties the applications of wrought magnesium alloys is still limited due to insufficient low temperature formability, which is directly attributed to an inadequate texture and microstructure development during thermomechanical processing. By contrast to typical wrought Mg alloys (e.g. AZ31, ZK60) which develop sharp deformation textures associated with strong mechanical anisotropy, rare earth (RE)-containing Mg alloys develop much weaker and less common textures that contribute to the enhancement of ambient formability and the reduction of the mechanical anisotropy. Although the effect of RE additions on randomizing the texture has been reported, the mechanisms of the observed texture modification are still not conclusively understood. The objective of this project is to conduct comprehensive investigations of deformation and recrystallization of Mg-RE alloys that will shed a new light on design strategies of Mg wrought alloys with optimized strength and ductility. The main focus is set on investigating single RE additions and exploiting their influence on the deformation characteristics, the recrystallization mechanisms, and the corresponding texture development. By identifying the controlling mechanisms, we should be able to derive a concept for microstructure and texture engineering for optimized mechanical properties.