Phase Evolution and Dynamic Response of Tungsten-Zirconium Alloys: Insights into W₂Zr Inhibition via W/Zr Ratio...

The formation of coarse brittle W₂Zr phases severely limits the dynamic mechanical performance of energetic W-Zr structural materials. In this work, Ti and Ni were introduced into the W-Zr system to modify the phase evolution during sintering, and three alloys with different Zr atomic concentrations, W_xZr_85-xTi_7.5Ni_7.5 (x = 45, 55, and 65), were prepared by vacuum sintering. Microstructural characterization showed that the W₄₅Zr₄₀Ti_7.5Ni_7.5 alloy contained abundant coarse micron-sized W₂Zr particles, whereas both the W₅₅Zr₃₀Ti_7.5Ni_7.5 and W₆₅Zr₂₀Ti_7.5Ni_7.5 alloys exhibited a lower fraction of W₂Zr together with a much finer characteristic size. In particular, decreasing the Zr content reduced the characteristic size of W₂Zr from several micrometers to below 200 nm. Interrupted sintering and thermal analyses suggest that the preferential formation of a Zr(Ti) solid solution and a Zr-Ti-Ni-rich ternary phase at lower temperatures reduces the local availability of free Zr for reaction with W, thereby suppressing the nucleation and growth of W₂Zr. Correspondingly, the dynamic compressive strength increased from 1054 MPa for W₄₅Zr₄₀Ti_7.5Ni_7.5 to 1720 MPa for W₆₅Zr₂₀Ti_7.5Ni_7.5. In addition, the W₆₅Zr₂₀Ti_7.5Ni_7.5 alloy maintained pronounced impact-induced reaction behavior despite its lower Zr content. These results indicate that tailoring the W/Zr ratio in the Ti/Ni-containing W-Zr system provides a feasible route to regulate W₂Zr formation and improve the compressive response under dynamic loading.