Fig. 1

Monte Carlo simulations of a two-step cooling transformation in the AlCoCrFeNi HEA. The atomic distributions for a series of different temperatures are illustrated, using supercells, composed of 12 × 12 × 24 cubic unit cells, where each unit cell contains one α and one β site. The supercells are “cut” to highlight configurational ordering, such that the side surfaces contain Al-rich α sites, and the top surface contains Al-poor β sites. Based upon the element-specific long-range order parameters (Fig. 3c), we find that the high-temperature phase is a disordered solid solution, which transitions to a partially ordered phase during cooling to 800 °C. Upon further cooling, the partially ordered phase transforms into a mixture of disordered Cr-Fe-enriched BCC and strongly ordered Al-Co-Ni-enriched B2 phases