Combined with the actual distribution characteristics of tungsten fibers and metallic glass matrix, a three-dimensional (3D) mesoscale finite element (FE) geometric model of a long rod of tungsten fiber-reinforced metallic glass composite was established, and the coupled thermo-mechanical constitutive model was used to describe the high strength and high shear sensitivity of metallic glass matrix. FE simulations on the oblique penetration/perforation of composite and tungsten alloy long rods into steel targets were carried out combined with related oblique penetrating tests, and comparative analyses on the deformation and failure characteristics of projectiles and targets were conducted. Furthermore, the influences of oblique angle and impact velocity on the ‘self-sharpening’ behavior of composite long rods and the corresponding ballistic performance were investigated in detail. Related analysis shows that in the oblique impact condition, due to the asymmetrical characteristics of target resistance on the rod, the rod nose gradually sharpens into an asymmetrical pointed configuration, and certain deflection occurs in the trajectory. Consequently, the ‘self-sharpening’ behavior in the composite long rod is weakened to a certain extent, and thus a decay occurs in its penetrating property. Besides, the impact velocity also contributes to the ‘self-sharpening’ characteristics and the corresponding ballistic behavior in the oblique impact condition, and the decay of penetrating capability derived from the oblique angle is more remarkable at lower impact velocities. When the oblique angle increases to 50°, the composite long rod is hard to effectively penetrate the target at an impact velocity lower than 900 m/s, and ricochet becomes easy when it impacts under a higher oblique angle. The results are of good significance in predicting the penetrating ability of tungsten fiber-reinforced metallic glass matrix composite long rods and optimizing its impact attitude.

In order to compare the similarities and differences among the self-sharpening behavior as well as the corresponding ballistic performance of tungsten fiber/metallic glass matrix (WF/MG) composite long rod projectile with different fiber diameters, the deformation and failure characteristics of various WF/MG composite long rod projectile were investigated systematically integrated with related penetration test results and mesoscopic finite element (FE) simulation analysis. The two-dimensional (2D) and three-dimensional (3D) meso-scale FE geometric models of WF/MG composite long rod projectile were established according to the actual distribution characteristics of metallic glass matrix and tungsten fibers. A coupled ‘thermo-mechanical-free volume’ constitutive model was applied to characterize the high shear sensitivity as well as high strength of metallic glass matrix. Moreover, the transformation of deformation and failure modes of projectiles under different impact velocities was analyzed in detail. Related analysis demonstrated that due to the differences in the mechanical properties among the tungsten fibers with different diameters, i.e., bending resistance and shear resistance, etc., the corresponding composite long rod projectile exhibit different failure characteristics during the penetration process, which further affects their penetration/perforation performance. The impact velocity also plays an important role on the deformation and failure modes of composite long rod projectile and the corresponding penetration/perforation performance. When the impact velocity is relatively low, the fibers in the nose of composite rod projectile exhibits unstable buckling phenomenon and gradually disperse during the penetration process, which makes the projectile nose blunt at a certain extent. This induces the increase in the penetration resistance and decrease in the penetration performance. As the impact velocity increases, small-diameter fibers reflux along the nose periphery while large-diameter fibers fail in shear. The large-diameter fiber further strengthens the self-sharpening behavior as well as the penetration performance of projectile. When the impact velocity and fiber diameter reach a certain upper threshold values, the thickness of ‘edge layer’ in the rod nose is sharply reduced, and thus the self-sharpening performance is weakened, and the penetration capability of projectile is decayed again. Related research is beneficial to predicting the penetration/perforation performance of WF/MG composite long rod projectiles with different fiber diameters under different impact velocities, and optimizing the structural design of projectile as well as the impact velocity, etc.

To enhance the evaluation and prediction for service performance of hot-end components in equipment under the dynamic loads, a comprehensive study was conducted on Ni-based single crystal superalloys with diverse microstructures. This study involved a series of split Hopkinson tensile bar (SHTB) tests and related scanning electron microscopy (SEM) characterization. The influences of various factors, including the volume fraction of precipitation particles, phase coarsening, loading angle and strain rate, etc., on the dynamic tensile properties of superalloys were systematically investigated. Moreover, the relationships between these factors and the fracture morphology of alloys were thoroughly discussed. The results indicated that the microstructural features and strain rate have significant effect on the dynamic tensile properties of alloys, leading to a complex anisotropic characteristic occur in their dynamic tensile behaviors after phase coarsening. In general, the yielding strength displays a positive relationship with the tensile strength. As the volume fraction of precipitation particles or the strain rate increases, the alloy specimen gradually exhibits brittle fracture characteristics, with an increase in strength and a decrease in elongation. Besides, phase coarsening derived from the aging treatment significantly weakens the strength of alloys while enhancing their elongation, i.e., the specimens progressively show mixed fracture characteristics after phase coarsening, and both yielding strength and tensile ultimate strength gradually decrease while the elongation increases with the degree of phase coarsening. Furthermore, the strength and elongation of alloys at the loading angle of 55° are lower than those at the loading angle of 0°. Comparatively, for alloys with high volume fraction of precipitation particles and high degree of phase coarsening, the elongation achieves the maximum value at the loading angle of 55°. The corresponding variation characteristics are closely related to the fibrous zone and the cleavage plane on the fracture surface. Meanwhile, the variations in microstructure of materials and loading conditions affect the microcrack nucleation and fracture mode within the specimen, leading to various dynamic tensile properties in Ni-based single crystal superalloys. The present research and related results provide theoretical guidance and experimental data support for improving the mechanical performance of Ni-based single crystal superalloys and optimizing the design of hot-end components.