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

增材制造（AM）是指通过以逐层方式控制添加材料来构建3D对象以生产最终形状或接近最终形状的对象的新兴技术。钛合金是航空航天和生物医学工业中许多应用的关键。这种材料是AM的理想候选物，因为其固有的高成本与提取相关的众多挑战相关，并且由于其对氧气的高亲和力和加工困难而导致其复杂的制造。迄今为止，该系统AM的大部分工作主要集中在cpTi和Ti-6Al-4V的组织-工艺和性能关系上。在这种情况下，存在关于这些合金的凝固的显著知识差距，当考虑相应合金元素对快速凝固的影响时更是如此，并且甚至更少这些相互作用将如何在拓扑优化的组件的背景下演变。拟进行的研究将探索凝固条件、合金元素含量、凝固后的晶粒尺寸和演变零件几何形状之间的关系等现象。这些关系将允许开发适用于所有钛合金的先进微观结构-加工-性能-设计框架，迄今为止还不存在工具。这个框架将是解决所有微观结构控制问题的关键，包括合金开裂。Alcoa凭借其全球业务组合，以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，并为客户提供钛合金AM的解决方案和新方法。他们设想将该框架扩展到其他AM流程，提高他们在所有AM流程上的竞争力。该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中AM技术采用率方面的地位。此外，该项目还将培训一名懂AM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.