Properties in Reactive Structure Materials: ZrW2 and HfW2 – High Melting Temperatures, Densities, Hardness, and Exothermic Ignition Energies

Abstract

ZrW2 and HfW2 were prepared by melting the constituent elements in an arc‐furnace. By cooling through perictectic phase lines above approximately 2000 °C, samples of the nominal 1:2 composition were obtained as products consisting of two phases, of which approximately 95 % adopts the MgCu2 type structure and 5 % the W structure. In ZrW2 and in HfW2, the MgCu2 type structure enables efficient topological compact spacefilling of the smaller W atoms into the cavities of the three‐dimensional net constructed by the larger tetravalent metals Zr and Hf. Correspondingly, very dense and hard alloys are obtained which burn at a crash in air in a strong exothermic ignition reaction. These materials are non‐toxic.