Development of Laser Powder Bed Fusion process for Complex Concentrated Alloys (a.k.a. High Entropy Alloys)

复杂浓缩合金（又称高熵合金）在过去十五年中引起了冶金界的极大关注。在这些材料中，相对大量的元素（因此是复杂的）以相似的分数组合（因此是浓缩的），已被表明具有许多理想特性的潜力，从高强度到高温下的高稳定性。因此，它们在航空航天等高级应用领域引起兴趣也就不足为奇了。然而，这些合金中的一些很难用传统方法加工，高性能部件所需的复杂形状意味着增材制造，其中部件以粉末形式逐步从材料中构建，可能是最有效的解决方案。然而，在这些过程中使用这些材料仍有许多未知之处。这项工作将使用增材制造技术，如选择性激光熔化，来加工高熵合金。目的是确保适当的加工，产生适当的微观结构和低缺陷含量。一旦可靠的材料被加工，它将被表征，以确定其在添加剂制造形式相对于简单铸造的性能。从这一点开始，可以制造和测试特定部件的原型版本，或者改变合金的组成，以尝试和提高其增材制造能力，或者产生所需的特定材料行为或性能。

Complex Concentrated Alloys (also known as High Entropy Alloys) have caused much excitement in the metallurgy community in the last decade and a half. These materials, where a relatively large number of elements (hence complex) are combined at similar fractions (hence concentrated) have been indicated to possess the potential for many desirable properties, from high strength to high stability at high temperature. It is therefore unsurprising that they have attracted interest for advanced applications, such as in aerospace. However, some of these alloys can be difficult to process by conventional means, and the complex shapes required for high-performance components means that Additive Manufacturing, where parts are built up progressively from the material in powdered form, may be the most effective solution. Much remains unknown about using such materials in such processes however.The work will use Additive Manufacturing techniques, such as Selective Laser Melting, to process High Entropy Alloys. The aim will be to ensure suitable processing, yielding an appropriate microstructure and low defect content. Once reliable material has been processed, it will be characterised to determine its performance in additive manufactured form relative to simple casting. From this point, prototype versions of specific components could be made and tested, or the composition of the alloy altered to try and improve its Additive Manufacturability, or to generate specific material behaviours or properties which would be desirable.