Design of novel crack-resistant aluminium alloys for additive manufacturing

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The manufacturing sector is critical to the Canadian economy, accounting for 10% of the GDP and 1.7 million jobs. Additive manufacturing (AM) is a revolutionary approach to manufacturing, in which materials are `printed' one layer at a time to create parts that are designed for optimal performance and that cannot be easily produced by traditional processes. Despite the potential benefits, less than 10% of Canadian manufacturers use metal AM, due to a limited scope of printable materials and poor quality of printed material. For example, many high strength aluminum (Al) alloys used for structural applications crack when they are printed. Therefore, the long-term vision of this research program is to eliminate scientific barriers to the use of metal AM to foster a more competitive and sustainable Canadian manufacturing sector. Over the next five years, I aim to develop crack resistant, high strength Al alloys suitable for AM by understanding the relationships between alloy composition, AM processing conditions, material microstructure, and the mechanical properties (e.g. strength, ductility). My research will focus on: (i) eliminating cracking in commercially available Al alloys through composition modifications, (ii) designing novel Al alloys with properties surpassing those of commercial alloys by exploring new composition spaces, (iii) developing recycling-grade high strength Al alloys by evaluating the effect of impurity elements (e.g. iron) on cracking and mechanical properties, and (iv) developing a tool to standardize crack measurements in AM. Thermodynamic simulations will guide the alloy design research by predicting the effect of alloy composition on the solidification and cracking behaviour. Samples with tailored compositions will be printed by laser metal deposition, a type of metal AM, and advanced characterization methods will be used to elucidate the mechanisms leading to crack elimination and strength improvement. My research will lead to competitive advantages for Canadian manufacturers by allowing them to print high quality parts with customized designs from high strength, lightweight Al alloys on demand, reducing development costs and time to market. Applied to the transportation sector, AM of Al alloys will lead to the creation of ultralightweight parts for vehicle lightweighting, which has the potential to reduce greenhouse gas emissions. The research will also lead to a more sustainable manufacturing sector by developing recycling-grade Al alloy raw materials for AM, which require less energy to produce that primary Al alloys. I will train 9 highly qualified personnel (HQP) within the research program, increasing the supply of highly skilled labour that is necessary to the adoption of metal AM by Canadian manufacturers. HQP will develop the scientific knowledge and technical skills (e.g. process optimization, design for AM) necessary for knowledge translation and implementation to industry end users.