where H m i x is defined as enthalpy of mixing, T is temperature, and Δ Δ S m i x is entropy of mixing respectively. Δ Δ H m i x and T Δ Δ S m i x continuously compete to determine the phase of the HEA material. Other important factors include atomic size of each element within the HEA, where Hume-Rothery rules and Akihisa Inoue [ Wikidata ] 's three empirical rules for bulk metallic glass play a role.