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

在过去的15年里，复杂的浓缩合金（也称为高熵合金）在冶金界引起了很大的轰动。这些材料，其中相对大量的元素（因此复杂）以相似的分数组合（因此浓缩），已被表明具有许多期望的性能的潜力，从高强度到高温下的高稳定性。因此，毫不奇怪，它们吸引了人们对先进应用的兴趣，例如在航空航天中。然而，这些合金中的一些可能难以通过传统方法进行加工，并且高性能部件所需的复杂形状意味着增材制造，其中零件以粉末形式逐渐构建，可能是最有效的解决方案。然而，在这样的过程中使用这样的材料还有很多未知之处。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，产生适当的显微组织和低缺陷含量。一旦加工出可靠的材料，将对其进行表征，以确定其在增材制造形式下相对于简单铸造的性能。从这一点出发，可以制造和测试特定组件的原型版本，或者改变合金的成分以尝试和改善其增材制造能力，或者产生所需的特定材料行为或特性。

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.