Grant: Discovery Grants Program - Individual

Manufacturing, maintenance, repair and overhaul of aero-engines in the Canadian aerospace sector generate over $3 billion in annual revenues. Significant advances have been made in recent decades regarding the development of new advanced high-temperature aerospace materials. However, the developments have not been adequately matched by advances in appropriate joining techniques for these new materials during manufacturing or for repair purposes. Since the discovery of a key strengthening phase, L12-type intermetallic precipitates, ?', in Co-based alloys, in 2006, there have been continued interests in the development of ?' precipitation strengthened Co-based superalloys with the intention that they could replace some nickel-based superalloys in next-generation aero-engines. Nevertheless, it is also known that increased ?' precipitates render these advanced materials difficult to weld by conventional welding techniques, due to increased susceptibility to grain boundary cracking. Since 2016, my research program has produced valuable understanding of the underlying microstructural causes of weld intergranular cracking in a newly developed ?' precipitation strengthened Co-based superalloy, CoWAlloy1. The research also yielded new knowledge that can be used to reduce the protracted processing time that generally hampers commercial application of transient liquid phase (TLP) bonding for effective joining of difficult-to-weld advanced structural materials. I plan to utilize these new findings to advance my research program on improved joining techniques for aerospace superalloys. In this proposed research, I will innovatively couple numerical modeling and simulations with experiments to explore how to combine special techniques of the hybrid laser-arc welding process with a new pre-weld microstructural modification to prevent or minimize weld cracking in the Co-based superalloy, CoWAlloy1. Furthermore, numerical simulations and experiments will be used to develop multi-stage diffusion to enhance solute diffusivity and reduce the processing time required to prevent the formation of deleterious micro-constituents during the TLP bonding of the Co-based superalloy. The proposed research will contribute crucial new knowledge that will advance our understanding of how to effectively and efficiently join components made of the newly emerging Co-based superalloys during manufacture and repair of aircraft and power generation engines. Aside from cost saving benefits and enhanced safety offered by improved joining and repair processes, effective use of advanced superalloys with higher temperature efficiencies would also help to lower the greenhouse emissions. The research will help train and equip at least 8 HQP with vital skills that have direct applications in the aerospace industry, a leading Canadian employer, and power generation industry, and will ultimately enhance Canada's industrial competitiveness in pioneering advanced joining technologies.