Properties In Reactive Structure Materials: Zrw(2)And Hfw2- High Melting Temperatures, Densities, Hardness, And Exothermic Ignition Energies

ZrW(2)and HfW(2)were prepared by melting the constituent elements in an arc-furnace. By cooling through perictectic phase lines above approximately 2000 degrees C, samples of the nominal 1:2 composition were obtained as products consisting of two phases, of which approximately 95 % adopts the MgCu(2)type structure and 5 % the W structure. In ZrW(2)and in HfW2, the MgCu(2)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.