Thermodynamic modelling and experimental validation of High Entropy Alloys containing Al, Co, Cr, Fe, Mo, Ni, Ta and W for high-temperature applications

The aim of the current project is to contribute to the design of novel High Entropy Alloys (HEAs) which meet targeted industrial needs, for instance the request for new high-temperature alloys. HEAs attracted a lot of attention due to their promising high temperature mechanical performance. Taking into account a very wide range of alloys that fall into this group of materials, using only experimental investigations would be insufficient in finding new compositions with attractive properties. The objective is achieved by thermodynamic modelling of the Al-Co-Cr-Fe-Mo-Ni-Ta-W system, through the CALPHAD method, in order to predict the best candidate elements and compositions which can give the required structure. The reliable and self-consistent database is obtained by assessing several important ternary systems and by adopting published assessments, if they were compatible with the models selected in this work. The reliability of the database is verified with experimental measurements performed during this work regarding the reference system Al-Co-Cr-Fe-Ni, as well as the critically selected published experimental data regarding several other multicomponent systems containing Mo and W. The synergy between modelling and experimental validation produce a highly reliable thermodynamic database which allows to screen and quickly identify high performance compositions, with a significant reduction in time and costs with respect to traditional trial and error experiments.