Phases in pure hafnium

Hafnium (Hf) is an important material for a wide range of applications including filaments, electrodes and control rods for nuclear reactors. Based on the equilibrium phase diagram, Hf exists in the form of a hexagonal closed-packed structure at temperature below 1743 degrees C or a body-centred cubic structure at temperature above 1743 degrees C. Here, we report the coexistence at ambient temperature of a hexagonal closed-packed structure, a body-centred cubic structure and a face-centred cubic structure with well-defined crystallographic orientation relationships in pure Hf produced by the iodide decomposition method.