Tantalum addition for dynamic-performance enhancement: achieving superior adiabatic shear response in novel tungsten heavy alloys

Conventional tungsten heavy alloy (WHA) armor-piercing projectiles exhibit a mushrooming effect during penetration that compromises their armor-piercing capability. Enhancing adiabatic shear sensitivity promotes self-sharpening behavior in WHA projectiles, thereby improving penetration performance. In this study, a novel 90 W(2Ta)-Ni-Fe-Cu alloy consisting of refined tungsten particles and γ phase was used. We characterized the quasi-static and dynamic compressive mechanical properties using a universal compression tester and a Hopkinson Pressure Bar (SHPB) device. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the microstructural evolution mechanism. The yield strength of the alloy increases from 917 MPa at 10⁻³ s⁻¹ to 1735 MPa at 6000 s⁻¹. Under dynamic deformation at a strain rate of 6000 s⁻¹, uniform deformation occurs in the alloy at 20 % deformation amount, adiabatic shear localization initiates at 40 % deformation amount, and adiabatic shear fracture takes place at 60 % deformation amount. The solid solution of Ta increases the compressive strength of tungsten alloys. The fine grain strengthening by Ta addition results in lower SHR and SRS, leading to higher adiabatic shear sensitivity in tungsten alloys.