Understanding plastic instability in next generation magnesium alloys

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In alloy and process design endeavours of highly formable wrought Mg alloys it is utterly important to account for material instability that occurs during plastic deformation. Especially, unwanted associated effects, such as strain localization, premature cracking and surface striations, should be avoided by understanding their mechanistic origins over a wide range of deformation conditions. Therefore, the present research proposal focuses on better understanding the link between dynamic microstructural phenomena, such as dynamic recovery, dynamic recrystallization and dynamic precipitation and the occurrence of plastic instability as a function of varying deformation conditions and alloy compositions. The main aims of the proposed project are to investigate the plastic flow instability (discontinuous yielding) in selected Mg-Mn-Nd and Mg-Mn-Ca alloys showing a good property profile of strength and formability, and provide a sound description of the governing mechanisms of plastic instability in the investigated alloys. Additionally, the conditions under which the plastic instability occurs as a result of presence of solute atoms and/or precipitates, and their interaction with mobile dislocations will be determined. Also of importance is whether possible synergetic effects of alloying elements play an increasing role in the onset of plastic instability, as compared to individual alloying additions, and whether such effects can be exploited to optimise texture and microstructure.The proposed research is of fundamental nature but has significant implications for sheet metal forming perspectives, particularly in the automotive and aircraft industries, where Mg alloys, due to their excellent specific strength, are becoming increasingly important. Acquiring advanced knowledge of the correlation between alloy composition, active deformation mechanisms and the occurrence of plastic instability greatly contributes towards improving the performance of next generation magnesium alloys by increasing their strength and forming capability.