Dynamic mechanical behavior and modified Johnson-Cook constitutive model of 95W-Ni-Fe-Co alloy under different processing conditions

• Microstructural Optimization Enhances Strength & Isotropy • Solution treatment refined tungsten grains and boosted binder-phase solubility, yielding 5% strength gain, while 20% rotary forging achieved 81% strength improvement. Low-deformation rotary-forged 95W exhibited isotropic behavior (no orientation-dependent strength variation in 0°-90° compression tests). • Strain Localization Emerges as Dynamic Loading Limit • Rotary-forged 95W demonstrated peak dynamic strength but developed localized deformation bands (shear instability precursors), whereas solution-treated alloy showed superior strain hardening and cross-microstructure deformation coordination under high-rate loading. • Modified JC Model Outperforms Classics with 2.3% Prediction Error • The MJC constitutive model, optimized via stress-equilibrium-validated data segmentation, reduced prediction errors to 2.3% across strain rates and processing states, decisively outperforming conventional JC models (>10% errors) in capturing tungsten alloy plasticity. Tungsten heavy alloys (W-Ni-Fe) have become critical materials in defense and aerospace applications due to their high density and superior mechanical properties, yet their constitutive models under dynamic loading remain incomplete. This study systematically investigates the mechanical behavior of a 95W-Ni-Fe-Co alloy fabricated through vacuum sintering, solution treatment, and rotary forging processes via quasi-static and dynamic compression testing. Microstructural characterization reveals that solution treatment significantly refines tungsten grains (30.5 μm vs. 45 μm in as-sintered state) while enhancing W/Co diffusion in the binder phase. Rotary forging introduces 20% plastic deformation, achieving 81% yield strength enhancement (1305 MPa vs. 720 MPa in as-sintered condition). Dynamic tests (1500 s −1 −6500 s −1 ) demonstrate distinct strain rate strengthening effects: solution-treated alloy exhibits optimal strain hardening capacity (B=1693 MPa) with homogeneous deformation, whereas rotary-forged specimens show higher susceptibility to adiabatic shear instability due to localized deformation band initiation. A modified Johnson-Cook (MJC) model incorporating strain-strain rate coupling coefficients ( C ₁− C ₅) reduces prediction errors to 2.3% (compared with 10%−30% errors from original JC model). Numerical simulations implemented through ABAQUS/VUMAT secondary development validate MJC model accuracy under high strain rates. These findings provide critical theoretical foundations and constitutive model support for tungsten alloy design under extreme service conditions, with future research focusing on fracture criteria and impact behavior investigation.