Relationships linking alloying elements, solidification, geometry and cracking during pulse laser additive manufacturing of Ti alloys

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Additive Manufacturing (AM) refers to an emerging class of technologies that build 3D objects by the controlled addition of materials in a layer-by-layer fashion to produce objects at or near their final shape. Ti alloys are key for many applications in the aerospace and biomedical industries. This material is an ideal candidate for AM due to its inherent high cost associated with the numerous challenges related to extraction, and from its complex manufacturing due to its high affinity to oxygen and difficulty in machining. To date, the bulk of the work on AM of this system primarily focused on microstructure-processing and properties relationships on cpTi and Ti-6Al-4V. In this context, a significant knowledge gap on the solidification of these alloys exist, more so when considering the effect of the respective alloying element on the rapid solidification, and even less how these interactions would be evolving in the context of a topology optimised component. The proposed research will explore phenomena such as the relationship between the solidification condition, the alloying element content, the solidified ß grain size and the evolutive part geometries. These relationships will permit the development of an advanced microstructure-processing-properties-design framework applicable to all Ti alloys, tools nonexistent to date. This framework will be key in solving all microstructural control issues, including alloy cracking. Alcoa, with its global portfolio of business, has entered the project with specific technological objectives to maintain their competitiveness and technological leadership in the field of AM, and to provide their customers with solutions and new methodologies for AM of Ti alloys. They envisaged to expend this framework to other AM processes, improving their competitiveness on all AM processes. The dissemination of the research will contribute to improve Canada's position in adoption rate of AM technologies for all industries having Alcoa as supplier. Moreover, this project will train an additional AM-literate HQP, mandatorily needed to adopt this disruptive technology.