Fundamental investigation of the mechanisms of deformation and recrystallisation of cold deformable Mg alloys micro-alloyed with are earth elements and microstructure optimization for the development of a new class of Mg-alloys.

具有六方密排晶体结构的常规镁锻造合金在室温下具有强烈受限的可成形性和显著的机械各向异性，这使得它们难以在工业过程中处理。似乎克服这些缺点的一类镁合金是用稀土（RE）元素如Ce或MM（混合稀土，主要成分为Ce的稀土元素的混合物）微合金化的那些。该材料可以冷轧到高变形程度，并且变形相当弱。稀土元素对冷变形性能和织构演化的影响主要是由于剪切带的强烈形成，但具体机制尚不清楚。也不清楚剪切带如何影响随后退火处理过程中的微观结构和织构演变。因此，本文提出的项目的目的是对这些合金的变形和再结晶机制进行基础研究。将生产不同合金成分的样品，使其变形并退火。高分辨率的SEM和TEM取向显微镜技术和三维取向显微镜的FIB-SEM，然后将被应用到不同的变形和再结晶程度的结晶样品。对变形和再结晶机制的正确理解对于这类有前途的材料的进一步发展至关重要。

Conventional magnesium wrought alloys with hexagonal close packed crystal structure suffer from a strongly limited formability at room temperature and a marked mechanical anisotropy which makes them difficult to handle in industrial processes. A class of Mg-alloys that seems to overcome these shortcomings is those micro-alloyed with rare-earth (RE) elements like Ce or MM (misch-metal, a mixture of rare earth elements with major constituent of Ce). The material can be cold rolled to high deformation degrees and the deformation is rather weak. The effects of RE elements on the cold deformability and texture evolution have been ascribed to the intense formation of shear bands but the detailed mechanisms remain largely unclear. It is also not understood how shear bands influence the microstructure and texture evolution during subsequent annealing treatments. Aim of the here presented project is, therefore, to perform a fundamental study on the deformation and recrystallisation mechanisms in these alloys. Samples of different alloy composition will be produced, deformed and annealed. High resolution orientation microscopy techniques in SEM and TEM and 3-dimensional orientation microscopy in a FIB-SEM will then be applied to characterise samples of different deformation and recrystallisation degree. A sound understanding of the deformation and recrystallisation mechanisms is essential for further development of this promising class of materials.