Development of tungsten heavy alloy reinforced by cubic zirconia through liquid-liquid doping and mechanical alloying methods

A new tungsten heavy alloy, which is characterized by fine yttria stabilized cubic zirconia (c-ZrO2(Y)) particles dispersed in the alloy, was developed by an ion-level liquide-liquid (L-L) doping technique combined with mechanical alloying. The microstructure and mechanical properties of tungsten heavy alloy were investigated, and the formation process and role of zirconia were discussed. Results show the zirconium element transforms in an order of Zr4+ to Zr(WO4)2 or 2Zr(WO4)2 nH2O to m-ZrO2 in the preparation process of powders. Finally, the c-ZrO2(Y) particles with size of 200-1000 nm are obtained in tungsten heavy alloy during sintering at 1520 °C for 90 min. Most of c-ZrO2(Y) particles are distributed within tungsten grains, and some c-ZrO2(Y) particles tend to be dispersed at the interfaces of tungsten grains, while a small number of c-ZrO2(Y) particles are dispersed in γ(Fe, Ni, W) matrix. The compressive strength of new alloy is improved approximately 8.2% than that of 93 W-4.9Ni-2.1Fe. This attributes to c-ZrO2(Y), which refines tungsten grain, lowers W-W contiguity and strengthens tungsten and γ(Fe, Ni, W) grains.