Unraveling of high strain rate deformation mechanisms in cold-sprayed CoCrFeMnNi: An integrated experimental and computational approach

High-entropy alloys (HEAs), particularly the CoCrFeMnNi system known as the Cantor alloy, have attracted significant interest for engineering applications due to outstanding mechanical properties. However, optimizing these properties, especially in cold-sprayed forms, requires deeper understanding of their deformation mechanisms. This study investigates the deformation response of the Cantor alloy and uses numerical analysis to determine when slip and twinning emerge as the primary mechanisms. For this purpose, Cantor alloy was subjected to cold spraying at a gas temperature of 1,223 K with an operating pressure of 4.9 MPa. A computational fluid dynamics (CFD) model was used to estimate particle velocity and impact temperature, while finite element method (FEM) simulations were applied to reveal jet-type morphology, indicative of severe localized deformation. The high-resolution transmission electron microscopy (HR-TEM) imaging of cantor alloy splat cross-sections showed outstanding deformability because of the extensive twin activities including the formation of twin bundles, nano shear bands, thin nanotwins, and dynamic recrystallization Molecular dynamic (MD) simulations were applied for calculating generalized stacking fault energy (GSFE) to estimate the critical resolved shear stress (CRSS) for slip and twinning. Results showed that the Cantor alloy, with an average grain size of 3.4 microns, exhibited a CRSS of 387 MPa for twinning. However, the CRSS for slip, as calculated using the Peierls–Nabarro (PN) model, was around 106 MPa. HR-TEM analysis results confirmed slip dominates near the interface, whereas twinning occurs farther away due to the higher strain-hardening rate of slip.