Investigation of Compressive Mechanical Properties and Microstructure Evolution of 93W-4.9Ni-2.1Fe Heavy Alloy under a Wide Range of Strain Rates

The compressive mechanical properties of the 93W-4.9Ni-2.1Fe heavy alloy were investigated across a wide range of strain rates (1.0 × 10⁻³-5.0 × 10³/s) using a mechanical test system (MTS810) and a Split Hopkinson Pressure Bar. The microstructure of the axial cross section of the specimens was subsequently analyzed using scanning electron microscopy, energy-dispersive X-ray spectrometry, and electron backscatter diffraction. The results revealed that under dynamic loading, the yield strength of the 93W-4.9Ni-2.1Fe heavy alloy showed increased strain rate sensitivity compared to quasi-static conditions. With increasing strain rate, the circle equivalent diameter of tungsten grains in the alloy continued to decrease, indicating a growing dominance in bearing the load and contributing to the deformation resistance. However, the work hardening capacity was reduced due to thermal softening effects under dynamic loading. Interface debonding between the tungsten grains and the matrix was observed after loading, and cracks initiated from weaker regions within the matrix, subsequently growing and intersecting. This study provides a theoretical basis for a comprehensive understanding of the high strain rate sensitivity and microstructural evolution of the 93W-4.9Ni-2.1Fe heavy alloy across a broad range of strain rates.