Engineering the Anisotropy of Magnesium Alloys for Enhanced Performance

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Magnesium is the lightest metal that can be used in load bearing applications in various alloy forms. However, current processing techniques for forming and shaping are limited to elevated temperatures, which drive high production costs and a negative environmental footprint. This award supports fundamental research to provide strategies for producing fracture-resistant Mg alloys, including during forming operations. A key departure from current thinking is to engineer an essential feature of these materials, the directionality of their properties, which is conventionally thought of as deleterious, hence to be mitigated. Accelerated insertion of Mg alloys is potentially transformative in a multi-billion dollar economy of the transportation industry. In addition, use of these lightweight structural materials will lead to reduction in fuel consumption and emissions with a positive impact on the environment, including in manufacturing. The project activities will create an interdisciplinary research environment for both undergraduate and graduate students and investigate teaching methods in processing and manufacturing. The research will elucidate the relationship between the plastic anisotropy of Mg alloys and their fracture resistance and formability. The underlying hypothesis is that the anisotropy of Mg alloys can be engineered to develop materials with unprecedented strength and ductility. To test the hypothesis, materials sharing the same chemical composition and microstructure but having different textures will be produced in bulk and sheet form and characterized for their plastic strength, formability and fracture properties. A metrics-based methodology will be developed for correlating plastic anisotropy with measures of fracture and formability. Discrete dislocation dynamics, continuum damage mechanics analyses and simulations as well as investigations of microscopic damage mechanisms will be carried out to gain further insight into the success or failure of such correlations. The project will therefore help answer important questions such as: (i) Is material anisotropy intrinsically deleterious? If not, how can it be engineered for enhanced performance? (ii) Does enhanced ductility translate into cost-effective formability? (iii) Are there any achievable textures that result in types of anisotropy that prevent shear failure? (iv) How does the anisotropy manifest at dislocation scales? Inquiry into these issues will follow a holistic approach that brings together materials science, mechanics and manufacturing.