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.

传统的六方密堆积晶体结构的镁合金在室温下的成形性受到很大的限制，并且存在明显的力学各向异性，这使得它们在工业加工中很难处理。一类似乎可以克服这些缺点的镁合金是那些微合金化的稀土(RE)元素，如Ce或MM(混合稀土元素，主要成分为Ce)。该材料可以冷轧到高变形度，但变形量较小。稀土元素对冷变形性和织构演化的影响被认为是由于剪切带的强烈形成，但具体机制尚不清楚。在后续的退火热处理过程中，剪切带如何影响显微组织和织构的演变也不是很清楚。因此，本项目的目的是对这些合金的变形和再结晶机制进行基础性研究。将产生不同合金成分的样品，进行变形和退火热处理。然后，将使用扫描电子显微镜和电子显微镜中的高分辨率取向显微镜技术以及FIB-SEM中的三维取向显微镜技术来表征不同变形和再结晶程度的样品。对变形和再结晶机制的正确理解对于进一步开发这类有希望的材料是至关重要的。

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.