Ultra-High Dynamic Strength of Additively Manufactured GRX-810 Under Coupled Conditions of High Strain Rate and Elevated Temperature

Abstract

Deformation mechanisms in CrCoNi-based oxide-dispersion-strengthened multi-principal element alloys (CrCoNi-based ODS-MPEA) have been extensively studied under quasi-static and low strain rate loading over a wide temperature range, yet their behavior at high strain rates and elevated temperatures remains poorly understood. In this work, we investigate the high strain rate response of the CrCoNi-based ODS-MPEA alloy GRX-810 and its non-ODS variant. The ODS variant contains a high density of hexagonal yttria nanoparticles that serve as the strengthening oxide phase. At high strain rates and ambient temperature, GRX-810 ODS exhibits higher dynamic strength, approximately 2.79 times its quasi-static strength, than both conventional alloys and its non-ODS variant because of the additional athermal strengthening provided by the nanoscale oxide dispersion. At high strain rates and elevated temperatures, however, GRX-810 ODS undergoes thermal softening. This response is consistent with dislocation confinement associated with the small interparticle spacing of the oxide dispersion, which limits the phonon-drag contribution, together with the temperature-dependent reduction of elastic constants that lowers the athermal strengthening terms, including the oxide-related contribution. Additional weakening of the solute-pinning mechanism at elevated temperature further reduces the dynamic yield strength.