Origin of the yield stress anomaly in L12 2 intermetallics unveiled with physically informed machine-learning potentials

X Xu and X Zhang and E Bitzek and S Schmauder and B Grabowski, ACTA MATERIALIA, 281, 120423 (2024).

DOI: 10.1016/j.actamat.2024.120423

The yield stress anomaly of L12 2 intermetallics such as Ni3Al, 3 Al, Ni3Ga, 3 Ga, Co3(Al,W) 3 (Al,W) is controlled by the so-called Kear- Wilsdorf lock (KWL), of which the formation and unlocking are governed by dislocation cross-slip. Despite the importance of this anomalous behavior in L12 2-strengthened alloys, microscopic understanding of the KWL is limited. Here, molecular dynamics simulations are conducted by employing a dedicated machine-learning interatomic potential derived via physically informed active learning. The potential facilitates modeling of the dislocation behavior in Ni3Al 3 Al with near ab initio accuracy. KWL formation and unlocking are observed and analyzed. The unlocking stress demonstrates a pronounced temperature dependence, contradicting the assumptions of existing analytical models. A phenomenological model is proposed to effectively describe the atomistic unlocking stresses and extrapolate them to the macroscopic scale. The model is general and applicable to other L12 2 intermetallics. The acquired knowledge of KWLs provides a deeper understanding on the origin of the yield stress anomaly.

Return to Publications page