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.

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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.