Effect of increasing Ti content on the phase, interface, dynamic mechanical properties and ballistic performance of W–Ti–Zr alloys

Abstract W2Zr intermetallic is an important reason for the brittleness of W–Zr binary system. When W–Zr alloys are used as the energetic fragment, the integrity of a projectile cannot be maintained under the explosion even propellant loading process, resulting in severe fracture of the projectile. Moreover, due to the strong atomic bonding in W2Zr intermetallic, the oxidation reactivity of the Zr atoms with oxygen in the air is significantly suppressed, limiting the effective energy release of W–Zr fragment under high-speed impacting process. In this study, based on the thermodynamic analysis, 30W-xTi-(70-x)Zr (wt.%) alloys were designed and prepared by powder metallurgy. It was found that the formation and stabilization temperature of W2Zr phase can be reduced by increasing the Ti content. The hard W-rich phase has changed from the coarse W2Zr particle to fine W2Zr precipitate and finally to the WTix solid solution with the increase of Ti content. Meanwhile, a semi-coherent interface between fine W2Zr precipitate and α matrix and even coherent interface between WTix and α matrix were formed, by which the intergranular fracture ratio between W-rich phases and α matrix was significantly decreased in the W–Ti–Zr alloys. Consequently, higher dynamic compressive strength and ductility of the W–Ti–Zr alloys were obtained by increasing the Ti content. The selected W–Ti–Zr alloys with high strength and proper failure strain exhibited good penetration and energy-releasing behaviors when they were used as reactive bullet launching at a velocity of about 1250 m/s. The relationship among the dynamic compressive strength, ductility and ballistic performance of the W–Ti–Zr reactive structural alloys was also discussed in detail.