Quasicrystals under pressure: a comparison between Ti–Zr–Ni and Al–Cu–Fe icosahedral phases

Single-phase icosahedral phases (i-phases) of TiZrNi and AlCuFe alloys were obtained by single roller melt-spinning in protective argon atmosphere. The high-pressure (up to 25 GPa) compression properties of i-TiZrNi and i-AlCuFe were investigated by in situ energy-dispersive synchrotron radiation (SR) diffraction experiments using a gas-membrane diamond-anvil cell. In contrast to i-AlCuFe, reproducible deviations from the Birch–Murnaghan equation of state were noticed in the form of hysterezis loops during the first compression cycles of i-TiZrNi alloys. This response of quasicrystalline matter to hydrostatic pressure conditions is here reported for the first time. Plastic deformation processes and effects related to the small grain size of the rapidly-quenched TiZrNi alloys are tentatively considered as possible explanations

Measurement and analysis of nonhydrostatic lattice strain component in niobium to 145 GPa under various fluid pressure-transmitting media

The d spacings in niobium have been measured to 145 GPa with a diamond anvil cell using a fluid13; pressure-transmitting medium methanolx2013;ethanolx2013;water MEW mixture, or helium. The13; conventional geometry, wherein the primary x-ray beam passes parallel to the load axis with image13; plate, has been used to record the diffraction patterns. The analysis of the d spacings using the lattice13; strain equations indicates the presence of nonhydrostatic stress component with both MEW and He13; pressure-transmitting media in the pressure ranges that are well below the freezing pressure of the13; pressure-transmitting medium. A method to correct the measured d spacings for the nonhydrostatic13; pressure effect is suggested. This study clearly emphasizes the need to carefully analyze the data for13; the nonhydrostatic compression effects even if the experiments are performed with fluid13; pressure-transmitting medium