Nanocrystalline iron at high pressure

X-ray diffraction measurements were performed on nanocrystalline iron up to 46 GPa. For nanocrystalline epsilon -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 epsilon -Fe is 22.9 +/-0.2 Angstrom (3), compared to 22.3 +/-0.2 Angstrom (3) for large-grained epsilon -Fe. No significant grain growth was observed to occur under pressure. (C) 2001 American Institute of Physics.