Implementation of Magnesium Alloy AZ91D on Wire and Arc Additive Manufacturing

As progress on Additive Manufacturing (AM) techniques focusing on ceramics and polymers evolve, metals continue to be a challenging material to manipulate when fabricating products. Current methods, such as Selective Laser Sintering (SLS) and Electron Beam Melting (EBM) face many intrinsic limitations due to the nature of their processes. Material selection, elevated cost and low deposition rates are some of the barriers to consider when one of these methods is to be used for the fabrication of engineering products. The research here presented demonstrates the use of a Wire and Arc Additive Manufacturing (WAAM) system for the creation of metallic specimens. This project explored the feasibility of fabricating elements made out of Magnesium alloys with the potential to be used in biomedical applications. It is known that the elastic modulus of magnesium (41-45 GPa) is more similar of that of natural bone (3-20 GPa) comparing with other metals. Thus, stress shielding phenomena can be reduced. Furthermore, the decomposition of Magnesium represents no harm inside the human body, since it is an essential element in the body and its decomposition products can be easily excreted through the urine. By alloying magnesium with aluminum and zinc, or rare earths such as Yttrium, Neodymium, Cerium, and Dysprosium the structural integrity of specimens inside the human body can be assured. However, the in-vivo corrosion rates of these products can be accelerated by the presence of impurities, voids, or segregation created during the manufacturing process. Fast corrosion rates would produce improper healing, which, in turn, involves subsequent surgical intervention. Magnesium alloy AZ91D based lines has been produced using the WAAM described in this research. Specimens created under different condition have been analyzed macro and microscopically in order to determine those parameters that yield visual and microstructural results