Accelerated exploration of multi-principal element alloys with solid solution phases

TLDR

High‑entropy alloy development expands candidate systems but creates a challenge of rapidly screening thousands for desired properties, and increasing element count raises intermetallic formation probability faster than configurational entropy, undermining the expected solid‑solution stability. The study aims to develop a rapid assessment method for structural metals by integrating calculated phase diagrams with simple rules based on phase presence, transformation temperatures, and microstructures. The authors evaluate over 130,000 alloy systems using the rule‑based phase‑diagram approach to pinpoint compositions suitable for detailed experimental investigation. They find that solid‑solution alloys become increasingly unlikely as the number of elements rises, contradicting the HEA premise that higher configurational entropy stabilizes disordered solid solutions.

Abstract

Abstract Recent multi-principal element, high entropy alloy (HEA) development strategies vastly expand the number of candidate alloy systems, but also pose a new challenge—how to rapidly screen thousands of candidate alloy systems for targeted properties. Here we develop a new approach to rapidly assess structural metals by combining calculated phase diagrams with simple rules based on the phases present, their transformation temperatures and useful microstructures. We evaluate over 130,000 alloy systems, identifying promising compositions for more time-intensive experimental studies. We find the surprising result that solid solution alloys become less likely as the number of alloy elements increases. This contradicts the major premise of HEAs—that increased configurational entropy increases the stability of disordered solid solution phases. As the number of elements increases, the configurational entropy rises slowly while the probability of at least one pair of elements favouring formation of intermetallic compounds increases more rapidly, explaining this apparent contradiction.