Nanocrystalline iron at high pressure

X-ray diffraction measurements were performed on nanocrystalline iron up to 46 GPa. For nanocrystalline ε-Fe, analysis of lattice parameter data provides a bulk modulus, K, of 179±8 GPa and a pressure derivative of the bulk modulus, K′, of 3.6±0.7, similar to the large-grained control sample. The extrapolated zero-pressure unit cell volume of nanocrystalline ε-Fe is 22.9±0.2 Å3, compared to 22.3±0.2 Å3 for large-grained ε-Fe. No significant grain growth was observed to occur under pressure.