  High Entropy Alloys (HEAs) contain near equimolar amounts of five or more
elements and are a compelling space for materials design. Great emphasis is
placed on identifying HEAs that form a homogeneous solid-solution, but the
design of such HEAs is hindered by the difficulty of navigating stability
relationships in high-component spaces. Traditional phase diagrams use
barycentric coordinates to represent composition axes, which require D = (N -
1) spatial dimensions to represent an N-component system, meaning that HEA
systems with N > 4 components cannot be readily visualized. Here, we propose
forgoing barycentric composition axes in favor of two energy axes: a
formation-energy axis and a 'reaction energy' axis. These Inverse Hull Webs
offer an information-dense 2D representation that successfully capture complex
phase stability relationships in N > 4 component systems. We use our new
diagrams to visualize the transition of HEA solid-solutions from
high-temperature stability to metastability upon quenching, and identify
important thermodynamic features that are correlated with the persistence or
decomposition of metastable HEAs.
