Material flow and thermomechanical conditions during co-extrusion of cladded high-entropy alloy tubing via shear assisted processing and extrusion (ShAPE)

High-entropy alloys (HEAs) are highly promising candidates for nuclear fuel cladding due to their exceptional high-temperature mechanical properties and outstanding resistance to corrosion and irradiation. However, conventional HEA tube fabrication involves multiple thermomechanical steps, resulting in high costs and significant technical challenges, particularly when an additional corrosion-resistant cladding is required on the tube’s outer surface. As an innovative solid-phase processing technique, shear assisted processing and extrusion (ShAPE) enables the single-step co-extrusion of cladded tubes. By promoting dynamic recrystallization, ShAPE refines the material’s microstructure, enhancing both the mechanical properties and corrosion resistance of the final extrudates. Despite its potential, the application of ShAPE to the co-extrusion of cladded HEA tubes remains largely unexplored, primarily due to the high-temperature properties of HEAs, which accelerate tool wear and make identifying an optimal process window both time-consuming and costly. To address these challenges, this study develops a meshfree smoothed particle hydrodynamics (SPH) process model to investigate the ShAPE co-extrusion of copper-enriched equiatomic NiCoFeCr HEA tubes with a chromium cladding. Using this model, the relationships between process parameters, material flow patterns, thermomechanical conditions, and cladding quality are systematically analyzed. Simulation results reveal that the chromium material in the billet significantly influences die face temperature, contact conditions, and force and torque values. A lower die advance per revolution rate leads to higher temperatures, reduced force and torque, increased slipping contact conditions, and greater chromium dispersion within the extrudate. Material flow primarily follows a helical pattern, with the core billet material remaining in the tube core and the cladding billet material depositing onto the outer tube surface. The developed process model and simulation results offer valuable insights into the complex physics of ShAPE co-extrusion of cladded HEA tubes, providing a cost-efficient approach to refining process parameters, optimizing tooling and billet design, and guiding future experimental studies.