Development of a descriptor-based database for high-entropy ultra-high-temperature diboride ceramics

High-entropy ultra-high-temperature ceramics are a new frontier of material discovery due to their many beneficial material properties. Some of these properties are high heat resistance, corrosive and ware resistance, as well as possessing high hardness. Recent interest in hypersonic material design proves to be viable due to their ability to withstand extreme environments such as those encountered with hypersonic flight. Limited experimental data plagues high-entropy ceramics due to their recent discovery within the past ten years. This study focuses on gathering as much information towards high-entropy diborides which has gained interest in the aerospace industry. Descriptors are used to capture material properties of high-entropy diborides to predict the phase of these materials. Such descriptors are categorized as either elemental descriptor, thermodynamic descriptors and Density functional theory descriptors. Descriptors are obtained from various literature along with some of the data provided on high-entropy diborides. The database focuses exclusively on equimolar concentrations of transition metal diboride constituents. Missing datapoints for descriptors are calculated with formulas originating from the rule of mixture. Some descriptors require density functional theory calculations which require time-extensive computational power. A total of 333 high-entropy diborides are found within the database with thirty-four descriptors. Once descriptor data entries are submitted in the database, key descriptors are plotted to identify trends for phase stability. Vital descriptors that are essential in phase predictions stem from total valence electron concentrations, the disordered enthalpy-entropy descriptor, enthalpy cost, entropy-formation ability, lattice size difference, and volume difference.