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

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, WxZr85−xTi7.5Ni7.5 (x = 45, 55, and 65), were prepared by vacuum sintering. Microstructural characterization showed that the W45Zr40Ti7.5Ni7.5 alloy contained abundant coarse micron-sized W2Zr particles, whereas both the W55Zr30Ti7.5Ni7.5 and W65Zr20Ti7.5Ni7.5 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 W45Zr40Ti7.5Ni7.5 to 1720 MPa for W65Zr20Ti7.5Ni7.5. In addition, the W65Zr20Ti7.5Ni7.5 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.