In our continuous efforts to extend OCAS’ alloy production capabilities within our Metal Processing Centre, we cast, processed and characterised various High Entropy Alloys. The high-entropy alloy concept is based on the idea that high mixing entropy can promote the formation of stable single-phase microstructures. In more recent years, the concept has been broadened to ‘compositionally complex alloys’, with combinations of minimum three elements in ranges of 5 to 35%. These compositionally complex alloys can offer an infinite pool of new alloys with unexplored properties. Our unique experimental high throughput flow methodology enables OCAS to rapidly screen high numbers of formulations. It is exactly that which OCAS is putting into practice within the Horizon Europe project FORGE.

The Forge consortium aims to develop a set of cost-effective highly protective coatings, based on novel compositionally complex materials – both metal alloys and ceramics – to provide the required hardness, chemical stability and gas barrier properties for challenging applications. OCAS’s role in this project is to perform a first screening of the compositionally complex alloys. By pioneering unknown alloy processing at lab-scale, OCAS makes it possible to gather enough data to train and feed the machine learning model. Despite the huge number of available hardness values in literature for high entropy alloys and compositionally complex alloys, the need for a fast way to provide experimental data remains, as it is the only way to support databases and machine learning. Various alloying elements are not only present in large quantities in HEA but several of them have high (e.g. Ti, Cr & V) to very high (Nb, Mo, Ta & W) melting points, which makes the manufacturing of these alloys challenging. In addition, these elements can be very reactive to most crucibles. To avoid time-consuming iterations in a high-throughput flow, anticipating the selection of raw materials or pre-alloys and crucibles is crucial.

Next to our activities within FORGE, OCAS is also working on upscaling the production of the most known HEA: the Cantor’s alloy. OCAS successfully cast a 100 kg homogeneous Cantor’s CoCrFeMnNi high entropy alloy via vacuum induction melting. First processing and characterisation gave good results, and a more detailed analysis is on-going.