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

加性制造(AM)指的是一种新兴的技术，它通过逐层有控制地添加材料来制造3D对象，以产生最终形状或接近最终形状的对象。钛合金在航空航天和生物医学行业的许多应用中都是关键。这种材料是AM的理想候选材料，因为它固有的高成本与与提取相关的众多挑战相关，以及由于其对氧的高亲和力和机械加工的难度而导致的复杂制造。到目前为止，该系统中AM的大部分工作主要集中在cpTi和Ti-6Al-4V的组织-加工和性能关系上。在这种情况下，在这些合金的凝固方面存在很大的知识差距，当考虑到相应的合金元素对快速凝固的影响时，尤其如此，而在拓扑优化的成分的背景下，更少地考虑这些相互作用将如何演变。该研究将探索凝固条件、合金元素含量、凝固贝晶尺寸与零件几何形状演变之间的关系等现象。这些关系将允许开发适用于所有钛合金的先进的微结构-加工-性能-设计框架，这是迄今为止尚不存在的工具。这一框架将是解决包括合金开裂在内的所有微观结构控制问题的关键。凭借其全球业务组合，美国铝业带着特定的技术目标进入该项目，以保持其在AM领域的竞争力和技术领先地位，并为其客户提供钛合金AM的解决方案和新方法。他们设想将此框架扩展到其他AM流程，从而提高他们在所有AM流程上的竞争力。这项研究的传播将有助于提高加拿大在所有以美国铝业为供应商的行业采用AM技术方面的地位。此外，该项目将培训一名额外的具备AM素养的HQP，这是采用这种颠覆性技术所必需的。

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.