The name of High Entropy Alloy (HEA) first appeared in the paper by Yeh et al. (Advanced Engineering Materials, 6(5) (2004) 299.) published in 2004. The name was given because the authors found that when five or more components with equal/near equal atomic fractions were mixed together, simple solid solution phases instead of multiple intermetallic phases would form. Using a two-step approach a thermodynamic database can be developed in a reasonable time frame and this will enable the use of the CALPHAD method as design tool for HEAs or multi-principal element alloys.