Ab initio simulation of segregation at oxide-metal interfaces in GRX-810 alloy

The recently identified multiprincipal-element alloy (MEA), known as GRX-810, exhibits a dramatic improvement in the creep resistance at elevated temperatures. Initial studies have identified segregation atmospheres around the oxide-dispersion particles, which likely contribute to this phenomenon. However, the many details remain elusive, especially the co-segregation effects. Such effects include both substitutional and interstitial type segregation, leading to a complex alloying environment. To investigate these segregation effects, Monte Carlo/ab initio based molecular dynamics (MC/AIMD) hybrid simulations were performed. Coupled with an algorithm to identify potential interstitial sites, evaluation of the joint interstitial and substitutional segregation events was made possible. The simulations have revealed critical elements of carbon segregation near the oxide-dispersoid particles, where carbon atoms are repelled from the oxygen-terminated metal-yttria interface but attracted to the yttrium-terminated interface. This discovery identifies critical distinctions between yttrium-based oxide dispersoids, which control critical solute atmospheres.